If you get the SDL_GetDesktopDisplayMode_REAL error on your Macbook M1 when launching CSGO, then do as written below.
1. Add launch options to Steam for CSGO:-w 1440 -h 900 -fullscreen
2. Launch CSGO via Steam
3. Click Ignore or Always Ignore the SDL_GetDesktopDisplayMode_REAL error
4. Enjoy