This topic is as old as it can be and has been requested a lot of times during the years now either on the forum or on external sites like reddit/gamefaq sites.

Players don't want the camera forced to dynamically auto-adjust in the position you are running during legacy mode with a gamepad.
If you play legacy mode with a mouse you can fix the camera with holding the left mouse button down and don't get this issue.
This is a disadvantage for gamepad users compared to mouse/keyboard.

During hunting you want to check the spawnpoints fast, so you just want to move along them and point the camera to that spawnpoint. Because of the autoadjust it will give you a blurry image, which your eyes try to focus but because it is dynamical you can't stop the autoadjust completly, it will always accelerate a little.
It is like trying to balance a value to 277.22 but your gamepad only allows camera adjustments in 30 incremental. So you are either to fast or to slow with the correction on your right analog stick.

Some players reported it because of motion sickness effects too...