COVID. People start working from home or otherwise spending more time on computers instead of going outside, so they buy higher-end computers. Lockdowns end, people start picking the lower-end models again. On multi-threaded tasks, the difference between more and fewer cores is larger than the incremental improvements in per-thread performance over a couple years, so replacing older high core count CPUs with newer lower core count CPUs slightly lowers the average.
I don't buy this really. COVID to now is less than 1 laptop replacement cycle for non-techie users who will usually use a laptop until it stops functioning, and I don't think the techie users would upgrade at all if their only option is worse.
A lot of laptops stop functioning because somebody spills coffee in it or runs it over with their car. There are also many organizations that just replace computers on a 3-5 year schedule even if they still work.
And worse is multi-dimensional. If you shelled out for a high-end desktop in 2020 it could have 12 or 16 cores, but a new PC would have DDR5 instead of DDR4 and possibly more of it, a faster SSD, a CPU with faster single thread performance, and then you want that but can't justify 12+ cores this time so you get 6 or 8 and everything is better except the multi-thread performance, which is worse but only slightly.
The reticence to replace them also works against you. The person who spilled coffee in their machine can't justify replacing it with something that nice, so they get a downgrade. Everyone else still has a decent machine and keeps what they have. Then the person who spilled their drink is the only one changing the average.
