I don’t understand how they are supposed to “sell your data” if you just never use a Mozilla account and uncheck all the telemetry. Its not like they can secretly steal your data, since its Open Source.
It seems to me like just more FUD that Google is spreading to undermine our trust in free software.
Something to note, however, is that the new terms apply to the browser as a whole. If it was due to some of the opt-in services the browser includes (sync, account, translation, etc.), they could have specified the terms apply to those services instead.
Agree this isn’t necessarily malicious yet, but it definitely is not beneficial to users.