The cursor isn't controlling the planes and now when you try to move up, you roll down to the ground without control

Even in the tutorial when it tells you to control with cursor, nothing happens. When I tried to move back from the ammo resupply, my plane rolled until I plummeted to the ground

You arent the first one today reporting that issue.
no gamepad installed?
Can you use C+mouse in an airplane?
Does it happen with every plane?

i don´t know if what i think, but meaby has active the alternative control mode, in that the mouse is disabled to control the plane and only can move with keyboard

In settings there is a thing called “screen joystick” or sth like this. Make sure you have it turned off.

same here i think these this mouse control is the worst …after playing war thunder mouse control s which are very good, these controls are the worst i have used for mouse