Has technological progress slowed over the last 50 years?

..The very nature of expectations involves, to a certain extent, forecasting the future - something that as a race we're bad at. The one or two, and it is just one or two, people that managed to do it (probably accidentally) are the world's current multi-billionaires. ..
When I worked at Mother Shipton's Caves for a while we often told people of the amazingly accurate prophecies Mother Shipton made. Carriages without horses etc. She lived in a cave though :D

Mon0-Zer0 , what is loT?
The famous IoT (Internet of Things) hype curve... not be me I hasten to add...

It is more than self-boiling kettles, fridges that tell you when to buy milk again, and smart home security systems. It does have some great benefits. Connected appliances are more efficient and it includes things like autonomous farming equipment, wearable health monitors, smart factory equipment, wireless inventory trackers and biometric cybersecurity scanners.
opening the door for the cat but not a burglar.
Do we need to redefine ‘cat burglar’ as somebody who hides near a property waiting for the cat to come home and then sneaks inside when the door opens for the pet?:)
Slowed? We're living through technological marvels that would have been unbelievable even twenty years ago except in science fiction - deep fakes, the metaverse, cellular robots, mRNA vaccines, vat grown meat, quantum computing, boston dynamics, mass adoption of electric cars, GPT-3, IoT, reusable rockets, real time photorealistic games, drones, consumer 3d printing, self driving cars, room temperature superconductors, GPU's, Amazon Dash human labour free supermarkets, organ printing, spine repair, commercial brain/computer interfaces etc.

Sure, a chip is still a chip and manufacturers have run up against physical limits of the medium, but the technological developments are increasing incrementally each year - these increases are almost taken for granted but they're huge!

IMHO the last substantial technological breakthrough was the miniaturisation of computers accompanied by an exponential growth in computing power that really got going in the 80s and is still ongoing today. That's about 40 years which makes it fairly recent compared to the other breakthroughs. It remains to be seen if it has a developmental wall as does older tech like aircraft and motorised vehicles.

Off the top of my head computers have had a significant impact on scientific research for their ability to store and correlate data; on machinery in general through their ability to fine-tune and automate performance, and on entertainment through their capacity for creating virtual worlds. CPUs in PCs no longer double in performance every 18 months since a limit has been reached as to how small one can make the transistors and how fast one can run the CPUs without them melting. But new applications are found for computer tech every day, so we haven't reached a wall yet in that department. That covers deep fakes, the metaverse, cellular robots, photorealistic games, self driving cars, GPUs, IoT, boston dynamics, Amazon Dash human labour free supermarkets and GPT-3. Time will tell whether this finally reaches a saturation point, in that machinery can't be fine-tuned or automated any further.

mRNA is new technology (actually it goes back to the 90s). The problem with it, as with all genetic engineering, is that we didn't invent the original biological machine which is so fantastically complex that we are decades away from fully understanding its workings - if we ever succeed in fully understanding them. It's a bit like developing a computer programme. Typically, a programmer spends twice as much time ironing out the bugs in a programme as he spends creating the programme in the first place. This is because the human brain can process only so much complexity at a time, making it impossible to foresee all the mutual cause and effect in very complex structures.

A living organism is far more complex than the most complex computer programme and the problem is made worse by the fact that - unlike with computer programmes - defects in genetic programming can sometimes take years to manifest themselves. The mRNA vaccine is a good example of this. Since its implementation all sorts of unexpected side-effects have appeared and we will need years to fully evaluate them. Genetic engineering is dangerous and IMHO substantial genetic engineering is reckless.

To briefly cover the rest:

Vat grown meat
I came across this article - Lab-grown meat is supposed to be inevitable. The science tells a different story. - which I found fascinating in that David Humbird, a UC Berkeley-trained chemical engineer, mentions the "walls of no" - technological limits that no amount of ingenuity can cross: "his term for the barriers in thermodynamics, cell metabolism, bioreactor design, ingredient costs, facility construction, and other factors that will need to be overcome before cultivated protein can be produced cheaply enough to displace traditional meat. “And it’s a fractal no,” he told me. “You see the big no, but every big no is made up of a hundred little nos.”"

Reusable rockets
Time will tell if reusability is a substantial breakthrough in launch costs or just an incremental improvement. At present, Space X charges $62 million for the launch of a new Falcon 9 and $50 million for a reused Falcon 9. We'll see if the latter price goes down. For now it represents a 12,5% saving which isn't such a big deal.

These represent the ability to make batteries light enough to allow for brief flights. Fun but I wouldn't call it a lifestyle-transforming breakthrough.

3D printing
Remember when 3D printing was going to revolutionise industry? That was until the penny dropped that it is impossible to mass-produce 3D objects since the printing process is so slow. Great for individual items but not for anything required in quantity.

Room Temperature Superconductors, organ printing, spine repair, commercial brain/computer interfaces
I don't know to what extent these can be made to work, will be of practical benefit and can be made cheap enough for widespread use.
I'm sure the first car wasn't a cost saving, nor adding the stirrup to the horse. Creating a nuclear bomb had a lot of side effects. Mankind's first flight in a balloon didn't alter travel, it took another 150 years or so for air transports to really be a thing. We didn't invent the human cell, but if that makes mRNA just another minor innovation, then why not claim that miniaturization of computers - or computers overall - are just a small step as we didn't invent the electron?
I don't refute that there are dangers with some innovations but if that is an argument why they are not breakthroughs, then pretty much any new technology is not it either. Morality and risk, nor full comprehension, does not make something less revolutionary or disruptive.
To me the argument to disregard the value of scientific or technological innovation for the last 50 years boils down to "I don't like it, so it doesn't count". That said, it's an interesting discussion and I'm glad you're sharing your view. It's thought provoking. I just don't agree with it. :D
It looks like Justin is on his own from the posters in this thread on the tech slow down idea. Is interesting to discuss though. As I type this on a mobile phone wirelessly connected to a fast internet connection in my home.
IMHO the last substantial technological breakthrough was the miniaturisation of computers accompanied by an exponential growth in computing power that really got going in the 80s and is still ongoing today.
I would assign different 'break through' events; events that were the final ones in a long series of occurrences. In the business world, the invention that really drove the adoption of personal computers was the spreadsheet (this has been noted by others). It doesn't matter how small or how inexpensive a computer might be, unless there is a beneficial use, there is no reason for adoption, and without a significant initial adoption, there is little incentive for ongoing enhancement. In the consumer world, the break through was the online chat room (this is my personal observation). This gave everyday people a reason to acquire computers that were low(ish) cost and transportable. This also relied on the widespread establishment of electricity and telephone networks. Looking back, one can identify these things as 'break through,' but, at the time, it was impossible to distinguish these from temporary fads.

For the the other present day items, I suggest it is too early to determine which will go on to be fads and which will make the leap to ubiquitous use.

Vat Grown Meat - There is a reason that space stories never address food production beyond hydroponics. The space and resources needed to raise animals is too great to be plausible. Loss of grazing land and concerns over livestock production methods are becoming a concern on Earth. Whether it is vat grown meat, plant-based meat substitutes, or something else, I see a pressure to maintain the current variety of food options in a different form.

Reusable Rockets - The current cost to escape Earth's gravity well is simply too great for space flight to be used in anything beyond one-off uses. Barring some other mechanism to get objects in space, I can see an ongoing economic pressure to drive further enhancements in repair and reuse and away from disposable products.

Predicting which technical products will make the leap into general usage is impossible. What is possible, is to identify underlying pressures that these product might reasonably address. There will not be a single event that drives this, rather there will be multiple, reinforcing forces that cause the leap from small scale applicability to widespread usage.

3D Printing - There are pressures to move away from the central, mass manufacturing model to a more distributed model. There are costs associated with large manufacturing facilities, large storage facilities, and product transportation. If consumers start to shift back from disposable products to repairing and maintaining existing products, there could be pressures to establish local printing facilities (ala current hardware stores). I'm not sure whether there would be enough justification to move to individual, in home 3D printing.

Drones (and Robots) - There are undeniable pressures on the 'last mile' of delivery. Either costs are going to have to escalate for manual delivery, low-cost alternative delivery methods will need to come into play, or people will need to return to pickup from a central location.