Typical problems are incorrectly assigned flight controls. Make sure to check all possible axes that might have been automatically assigned. My gaming mouse even has an axis that was assigned to something, I believe it was the ailerons in my case. Other mice have additional buttons that are assigned in windows, which could match the buttons in MSFS for trim or elevator. A last but less probable reason can be a broken controller that sends spikes or even a mobile phone disturbing the signals in the wire.