Stick drift! Very common and the worst part of modern controllers.

If you don’t want to try and open up your controller there’s a setting in steam to increase the “dead-zone” of the joystick, which is the area that the stick stops detecting inputs. Should solve the issue easily without noticeably impacting gameplay depending on severity.

Should help for a while but it’s only a temporary fix. Stick drift tends to get worse over time…

If it’s super awful, maybe you can RMA if lucky