Off the top of my mind; mouse & trackpad, sound stack, bluetooth stack, hd/4k content streaming, no hdr at all, using multiple displays with different dpis... I tried every recommended driver&setting for mouse&trackpad. They are all terrible compared to Macos. The whole story of using multiple displays with xrandr, xinerama etc. is a joke. Agreed; you get a better experience with Wayland regarding that but then you lose the ability to do screenshare for the most part (without doing hacky stuff instead of doing work).