Firefox is interesting because its roots as an open source project go back a long time and Mozilla has generally been one of the most open companies working in that space. That's lead a lot of people to identify as members of that community, which is good in some aspects but also means that you have a vocal group of people who appear to feel that having participated in a few Bugzilla issues over a few decades means that they should be consulted on every change.
Over the same time period, web browsers have gone from a hot new technology to a part of daily life for most people in developed countries, and that's created areas for conflict where someone at Mozilla is trying to figure out how to retain users against a hostile trillion-dollar company and coming to conclusions which are different than some of the more conservative members of the user community want. We saw this with things like XUL's deprecation where that feature was blocking a lot of improvements which benefit 100% of users and a small group of users felt very strongly that someone else should do the extensive amount of work needed to maintain and modernize a lightly-used feature.
Over the same time period, web browsers have gone from a hot new technology to a part of daily life for most people in developed countries, and that's created areas for conflict where someone at Mozilla is trying to figure out how to retain users against a hostile trillion-dollar company and coming to conclusions which are different than some of the more conservative members of the user community want. We saw this with things like XUL's deprecation where that feature was blocking a lot of improvements which benefit 100% of users and a small group of users felt very strongly that someone else should do the extensive amount of work needed to maintain and modernize a lightly-used feature.