AAA Games with anti-cheat that don't support Linux.
Video editing (DaVinci Resolve exists but is a pain to get up and running on many distros, KDenLive/OpenShot don't really cut it for most)
Adobe Suite (Photoshop/Lightroom specifically, and Premiere for Video Editing) - would like to see Affinity support Linux but hasn't happened so far. GIMP and DarkTable aren't really substitutions unless you pour a lot of time into them.
Tried moving to Linux on my laptop this past month, made it a month before a reinstall of Windows 11. Had issues with WiFi chip (managed to fix but had to edit config files deep in the system, not ideal), Fedora with LUKS encryption after a kernel update the keyboard wouldn't work to input the encryption key, no Windows Hello-like support (face ID). Had the most success with EndeavourOS but running Arch is a chore for most.
It's getting there, best it's ever been, but there's still hurdles.