I was disappointed to find that Firefox's tablet interface is just a blown-up phone interface. I have switched to using Edge instead because it looks like a proper desktop browser with a tab bar, and has integrated ad-blocking.
For me, the two biggest pain points I experience with Firefox is the lack of PWA support on desktop, and now the lack of a proper tablet interface. So I end up using Chrome/Edge on desktop for PWAs, and now I use Edge on tablet.
It's getting harder to stick with Firefox...