Fair enough, but a decent actor could probably work as well.

I'm pretty confident that you are wrong.

Browsers based on chromium do not have to follow exactly what the main branch is doing. If they want to keep supporting MV2 or support different rules for MV3, they can. Albeit it's a bit cumbersome.

Alternatively, in a similar fashion. Use "hail" to auto pause any app you want so they don't run in the background unintended.

https://f-droid.org/en/packages/com.aistra.hail/

Google playstore does not inject data in app packaging because it doesn't own the signature key. F-Droid, however, does. I mean, they own the signature, but they do not inject or modify apps. They could, though.