For me personally about 30% of my video game library, which don't function even with the various compatibility tools.

But when I started my YouTube channel I was using Openshot, which does not work on Linux, or at least it didn't for me. My old Lenovo Legion was largely incompatible with Linux too, as I tried a dual-boot with two different distros and still had to debug it all the time. (Thankfully not a problem on the Acer that replaced it.)

Linux is great, but it's not yet compatible with everything.