SSR: https://github.com/Exopandora/shouldersurfing
When opening inventories, in shoulder surfing mode, (with SSR's replace_default_perspective = true, to be exact, not sure if that affects anything) and SSR's keep_camera_out_of_head = true, the head is rendered when opening inventories, even if it shouldnt because the camera is inside or very near the player.

nvm i highly suspect this is on shoulder surfing's side