i bought the game on steam without seeng that it is not compatible with linux. until the april 8 update it worket fine in proton with my flysky i6x but now it doesn't work. i tried the linux demo in itch and it worked.

The reason that the linux version is not on Steam is that it's experimental and may not work on all linux distributions.

(However it is available here on Itch for those that wish to try it, send me a message and I will provide a solution).