Sounds like the same farce as with the forced Pixel 4a update. Not sure if they learned anything from that, other than to ignore the issues and move ahead anyway.
Pixel 4a units contained one of two different batteries, and only the one manufactured by a company called Lishen was downgraded. For the Pixel 6a, Google has decreed that the battery limits will be imposed when the cells hit 400 charge cycles. Beyond that, the risk of fire becomes too great—there have been reports of Pixel 6a phones bursting into flames.
Perhaps your Pixel 4a had a non-Lishen battery? But if Google degraded your battery perf as well, then I have no idea.
Yeah, that killed my battery... at least it got me a free battery replacement, even though actually getting that locally was a bit of a pain. Couldn't "reserve" or make an appointment ahead. Just call uBreakIFix and if they had one, come in. That Google did the release that broke the batteries after they had recalled all the spares from the fixit companies was really poorly timed.
Still using my 4a, though have been thinking of a switch to the 9XL.
