Current mouse sensitivity implementation is linked to FPS. The lower your frame rate, the faster your mouse sensitivity. The higher your frame rate, the lower your mouse sensitivity. Example: 60 fps is a lot more sensitive than 165+ fps. If your FPS fluctuates or you put on the "unrestricted" setting, your mouse sensitivity will constantly change and will feel inconsistent. There are constantly dropped inputs with the current implementation. If you want this to change change, probably send the PSO2NG support a ticket about this.