They opted firefox users into a data collection scheme they call PPA which works kind of like FLOC and uses the browser to gather information about what you do online, then they sell that data to advertisers by first sending it to yet another a third party who will assemble that data into reports for the advertisers. Then they basically said firefox users were too stupid to be trusted to opt-in, and it would be too hard to explain to such dumb users how selling their data was a good thing, so Mozilla had no choice but to force it on everyone by default without telling them about it. (https://web.archive.org/web/20240715112635/https://mastodon....)
I don't understand what you're talking about. Do you have a reference? All I can find are UI experiments, AFAICT "what impact to telemetry does this UI change make?"
I see some have addons.. but actually my point is precisely that I don't understand it - these addons can be auto installed? They can make requests? They're not on searchfox?