Just to add to this, I didn't see any tab grouping or tab stacking implementations in the proposal for #Firefox. That's not to say they're not being worked on, but don't get your hopes up.
But to talk about the design again, an estimated 70% of browser users are on #mobile. 70% of those using #Android and the majority of those using #Android13 with native #MaterialYou. I'm unsure why #Mozilla wouldn't design for them specifically a browser that looks and feels native and feels super fast.