It can be a bit buggy at times, but when it comes to just playing music with the screen locked, it’s perfect.
https://addons.mozilla.org/en-US/firefox/addon/video-background-play-fix/
Edit: I forgot to also mention that ad blocker extensions make sailing the seas on mobile much more manageable. Extentions, in general, have been a really nice addition.
I’m pretty sure extensions can request browsing data for some specific URLs rather than every site you visit. If an extension with functionality on one website asks for access to all of them, then yeah it’s a bad sign.
https://cheatsheetseries.owasp.org/cheatsheets/Browser_Extension_Vulnerabilities_Cheat_Sheet.html
The person you replied to is correct, and your link confirms it:
The extension does not just have this access, it has to request it from the user first.
Of course, an extension can request access to all browsing data, but Firefox will tell you about that before you install it. And better still, the extension this post is about, doesn’t even request this: