CAMERA mode rotates the camera without changing the yaw/pitch of the player. This causes unfixable bugs like broken nametag and particle rendering and causes problems when right-clicking things (since you're not actually looking at them).
PLAYER mode rotates the player: The client changes its own yaw/pitch according to the camera rotation. This fixes the bugs caused by camera mode.
This changes the default from CAMERA to the new PLAYER mode. The mode can be changed back in the config if it causes problems (anti-cheat plugins might not like how players rotate their head).
CAMERA mode rotates the camera without changing the yaw/pitch of the player. This causes unfixable bugs like broken nametag and particle rendering and causes problems when right-clicking things (since you're not actually looking at them).
PLAYER mode rotates the player: The client changes its own yaw/pitch according to the camera rotation. This fixes the bugs caused by camera mode.
This changes the default from CAMERA to the new PLAYER mode. The mode can be changed back in the config if it causes problems (anti-cheat plugins might not like how players rotate their head).