Do you have multiple monitors?
If so, one of them may be set to a higher/lower scale than the other monitor.
This will cause the game client itself to pick up the scaling of default monitor which will cause the mouse input to be read at an amplified rate.
In some rare situations this can also happen with a single monitor, but it -widely- occurs with remote assistance software given the scaling of the virtual display.
You should be able to adjust the scaling for each monitor here:
Control Panel -> Display ->
By default you
may have the checkbox unchecked - causing your monitors to have separate scaling options.
The scaling option is provided by Windows to allow for things to look more uniform between the monitors
Although a side effect of this causes the camera issue with games given that the 'much bigger' monitor is being treated as a smaller monitor.
With my setup, my middle monitor is 38 inches @ 1920x1080 and my other monitors are 24inches @ 1920x1080, which is how I first noticed this issue.
On my larger monitor, the camera would move around fine but as soon as I moved it to my other monitors, it would spazz out.