Any form of moving the ingame camera via the mouse (eg. Right-clicking, shift lock, and first person), will freeze the mouse in place after scrolling out in first person, toggling off the shift lock by pressing shift, and right-clicking. Right-clicking has a scuffy-ish patch made by the maintainer of Grapejuice, Brinker. It’s downloadable on Arch Linux at the Grapejuice Discord.
Ouch what stage is this a part of?