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.
> "enter your sn in this form to see if you qualify"
> enter sn
> "great, you'll hear from us in 2 weeks"
> 2 weeks pass
> "you're eligible! you can either have $50 or $100 towards a new phone"
> just bought a new phone, give me the 50
> "great, you'll hear from us in 2 weeks"
> 2 weeks pass
> "we use a 3rd party to issue refunds, download their app"
> download app
> setup account
> verify account
> enter bank info
> "great, you'll hear from us in 2 weeks"
> 2 weeks pass
> "sorry, we couldn't process your bank info"
> dammit, forgot app password
> recover app account
> re-verify app account
> reenter banking info
> "great, you'll hear from us in 2 weeks"
> 2 weeks pass
> "your bank info is verified. You'll get your refund within 2 weeks"
> 2 weeks pass
> money deposited
barely even worth it.