@eevee @glyph off the top of my head: go to the gdc site and try to seek a video, it'll crash the video player on Firefox. No webgpu on Linux, no webusb (which yes, I actually use), missing html/css features like anchors, the dev tools are broadly worse, background updates reliably cause issues (most recently the browser was leaking), Firefox android UI is busted often, it gets stuck in uninteractable states until you force restart it a few times, reliably if you try to use "add to home screen".