Pretty sure this is gimbal lock. To see what I mean:
- put a cube in a blank scene
- using the inspector, independently rotate it a little bit around x, y, z - works as expected
- now set x rotation to 90
- try rotate around y and z - note that z works identically to y rotation! You can no longer rotate z!
In the context of your game, I’m not sure what the best solution would be, but there’s a few possibilities. Check out some youtube tutorials on changing gravity controllers…