How to fix the problem of object distortion when rotating the camera?

Question

Unity

The weapon is attached to the camera, when I rotate it on the Y axis, the weapon is distorted. When I create a project and do something similar, it may or may not be distorted. I don't know what it depends on, but I want to deal with this problem once and for all! Any ideas how to fix this?
Initial camera position:

Looking up: