Is it a problem anymore with proton?
Or rather -- is testing the game on Linux via proton sufficient, or do you actually look for native Linux builds?
I'm honestly interested as a dev who recently released my game I worked on free time, and I decide to go the route of single Windows build + proton, since it makes the build and release process a little bit easier, since I have a custom CI/CD pipeline and adding a Linux support into it would take some time.
And as someone who has a Linux as a daily driver and game only on Linux, having the game run on it was important to me, but I honestly didn't see a reason why go with a native build and the additional trouble it would cause with testing - because now I can just test one windows build on my Linux desktop through proton, and be fairly sure that it runs OK on both.
That's my favorite thing about axolotls.
They do live in water, but if you neglect them enough (or feed them special [hormone] evolution stones), they will say "fuck this", grow legs, evolve into slamanders and leave.