[Solved] Why the rotation of the camera is slow when I set Quality settings at very low?

Hi everyone I need a little help.

I made a simple game where I can control the rotation of the player by moving the mouse. I made this with a script that it will be called every FixedUpdate.
The rotation works well when I set the quality of the game at Ultra

Game on with ultra settings

When I set the quality to very low or low the rotation is very slow

Game on with very low settings

How can I solve this problem?

So the problem I made is this.

I put the rotation code inside the FixedUpdate method of the script, which is wrong by reading some documentation. So I putted the code in the Update method and I get the right movements of the camera.