This is a kind of bizarre hitpiece. As noted on the previous post linked below: (1) Chrome -- the far and away most popular alternative -- is worse in every way, and (2) PIA, the company publishing the post, is owned by a (former?) malware purveyor: https://torrentfreak.com/private-internet-access-to-be-acqui...
This article is making this stuff out to be a way bigger deal than it is. The telemetry is basic, not hidden, and can be disabled with just a few clicks/taps.
You can check everything that is being sent to mozilla at:
about:telemetry
and as you can see there is nothing that identifies you. And even if i'm missing something, you can always disable telemetry and be sure that (unlike others) firefox will respect your config and won't be sending any data
