Edit: As rtxn and n0x0n point out, we can adjust settings in Firefox itself and expect them to stay applied, but any settings done within the websites for Mozilla’s services could be changed on the Mozilla end at any time. Probably best to have an extra layer to this just in case.

Yes. Yes it can, and you bet your bibby people will be watching to see if Mozilla bypassed those settings, not that they ever have in their multiple decades of existence.

You’ll also have to opt out of using Mozilla services like browsing and bookmark sync.