The faster I move my mouse, the slower the camera pans (PC)

https://streamable.com/41lizs

In the video, I'm continuously moving the same distance on my mousepad, but gradually increasing the speed. It makes it impossible to flick or look around too fast.

Anyone else having this issue? Hardware mouse is enabled, and any other setting that would increase input delay is turned off. (1080p, no upscaling, vsnyc off, Reflex on + boost, etc.)

Thanks.