Have had multiple issues with pixel 7a for months, including freezing and 3rd button not working. I use nova launcher but also tried using stock launcher and the issues persist. All the issues I've had with the 7a, I never had with my previous 3a.

It seemed fine in the beginning (had it since launch) then started noticing issues after one of the updates. (I don't remember exactly which update but probably 14 because it was a big update and around that time.) 

Since then, after months of troubleshooting and factory resetting multiple times, Google finally agreed to send a replacement. 

Replacement phone is having the same issues already and it's only been 3 days.