Which means my .config directory, which is under backup, is gonna be spammed with temporary and cache files. Though not XDG-compliant, at least ~/.mozilla was in place for decades and it’s already being excluded in my backup set on my machines.
Either they adopt XDG fully, putting cache files where they belong, or don’t just change things haphazardly for little benefit.
Not cache files if I understand correctly, they are using $HOME/.cache/mozilla for a long time already.
You can exclude $HOME/.config/mozilla from your back up all the same anyway if that causes you some issues.
I personally appreciate them not cluttering $HOME with this move. It is better than waiting another 21 years for them to support XDG spec fully by splitting share and config.
Which already is a huge improvement and better than bikeshedding for decades that they also should use $HOME/.local/share/mozilla in addition.