A really horrible solution to a device without the problem. Dragons Dogma 2 has the same problem, where the only workaround is to have the in-game mouse sensitivity set to its lowest, and the mouse DPI set to the highest, which is a common problem with Capcom releases.
It’s one of the many symptoms of “consolisation”, where a PC game has problems associated with console game design. In this instance, it’s designed to make possible very small adjustments via a joystick aka console controller thumbstick. However they applied that effect to mouse inputs as well, which is an absolute positioning device as opposed to relative, and does not need that effect.
Often seen in games by console developers who don’t seem to know how to write for the PC. Here we are 4 years later, and we are still stuck with this.