"Ey.
So I am getting this annoying bug since the changes. Now my cursor in-game is constantly moving on its own once I let go.
What I mean by this, is if I look to the right sharply, my character will continue to infinitely twirl in a circle to the right. If I look to the left slowly, a very slow spinning will occur.
Anyone have any clue why this is happening? It’s a fucking pain to be honest. Tried a restart and everything.
Is your mouse still moving on its own when the menu is open?
You’re in cinematic mode. I’m not sure what toggle is, maybe f4? anyway it’s under controls
No, it stops entirely. And my mouse itself works fine outside of the game.
No I’m not, although I appreciate the suggestion. It moves much more fluidly than Cinematic Mode- disabled it and enabled it to see that- and I tried deleting my profiles and settings beforehand, and yet it persists.
I deleted every file on my side, save my servers.dat and resource pack folder, and the error is still there. 
Restarted my PC, deleted all MC files twice over, and unplugged everything.
Something above made it work again.