When I toggle on Switch Roll and Yaw, I cannot roll anymore because it appears to make both the strafe keys (A and D) and the mouse X axis control yaw instead of the strafe keys controlling roll. Or maybe the strafe keys control both roll and yaw (I have the roll sensitivity way down). I can see a bit of roll happening, but way more yaw.

I am on Fabric 1.21.3

I just figured out why this happens. It doesn't automatically swap the keybinds for roll left/right and yaw left/right when you toggle this option.

This is working as intended. I don't want to modify player's settings arbitrarily when they change the config, so you'll have to do it manually.