If you get error SDL_GetDesktopDisplayMode_REAL on Macbook M1 CSGO launch, then next instructions is for you.
1. Add launch options in Steam for CSGO:
-w 1440 -h 900 -fullscreen
2. Launch CSGO via Steam
3. Press Ignore or Always Ignore on SDL_GetDesktopDisplayMode_REAL error window
4. Enjoy!