Since it's been mentioned a lot this week because of these changes, here's David Revoy's guide to a fully FOSS professional digital painting setup, not perfect because many, MANY things aren't working as they should yet (both the move to Wayland and to Appimage/Flatpak have complicated things and lots is broken), but he guides you to a setup that works today.
There's also the option of different commercial stuff (The Affinity suite, DaVinci products, etc.), but i'm a bit biased