I have a pixel 6a and it works great. However, I did run GrapheneOS shortly after I got it, so that may be why. I don't use the Stock OS.
So google might be trying to get you to buy the newest phone? I know apple likes to slow down their old phones so people upgrade, maybe Google does the same.
https://piped.video/watch?v=HNwWQ9zGT-8&t=0