I was surprised to find I had telemetry enabled. I could have sworn I disabled it, but it would have been a long time ago, so I was thinking maybe I remember it wrong.

I would like to see any source that may exist on it having been silently re-enabled. I know telemetry is anonymized and totally harmless or whatever, but re-enabling it behind my back would feel like such a breach of trust.

I keep a careful log of such stuff and I'm 100% sure that I disabled it on all machines here. This definitely got re-enabled silently at some point, I am trying to figure out when. Not having such crap is the reason I use Firefox so it is hard to express my disappointment at this.

It was re-enabled for me as well. browser.crashReports.unsubmittedCheck.autoSubmit2 and datareporting.healthreport.uploadEnabled

It didn't re-enable for me.

When did you disable it?

Ages ago, probably the first time Mozilla added telemetry to the browser.

Go interview people Mozilla. Less analytical data but you'll end up knowing your users.

Anecdotal and same for me (it's not re-enabled). I have not touched those telemetry settings for years, cannot say exactly when.