edit: https://bugzilla.mozilla.org/show_bug.cgi?id=1846224

in FF119+ the pref to make locale match en-US was deprecated, as long term RFP (and FPP might use it) want to be able to cover all languages etc - there's a lot of tightening to do, such as enforcing preferred languages to match specific defaults (i.e not changing the order or adding/removing any), maybe using a smaller subset of preferred languages - e.g es-ES as the only spanish one, and making the locale match the language (or a smaller subset of languages)

so this leaves us with changing users preferred language(s) but still leaking their locale. I think it only changes/leaks if your system locale matches the first part - e.g. my computer is en-CA (not really, it's an example), but I use en-US in the app, so it uses my system locale. If my system locale was de-DE it wouldn't change it - I'm not sure, it's not like I set up foreign language VMs

anyway, the fact remains that the pref is now somewhat useless, and when they cover all languages, then it becomes moot.

I do not want to make it inactive, because after prefCleaner is run, I do not know what Firefox will do. So we either remove it now, or leave it in for a while?

Anyone have any insight or thoughts?