[corney91]

FWIW I also use Fennec from F-Droid and I'm getting very slow behaviour and crashes with lots of tabs open (between 10-30). I don't have the theme change or tabs missing though.

I've been meaning to try different Firefox distributions though because switching away from Firefox isn't really an option for the reasons you've stated.

[anneessens]

Oh that's interesting, glad I'm not the only one. Maybe I will try the Google Play version instead.