Check the following general game and system settings:
Use Borderless display mode.
Make sure your GPU drivers are up to date.
Disable unnecessary third-party overlays.
Close applications that may interfere with the game.
Make sure Rainbow Six Siege itself runs normally without the product.
Note
If crashes continue after these checks, collect the crash information and contact support. The original documentation notes that persistent random crashes may require investigation of the specific product build.
Synthera Docs