Logical vs. actual resolution
Windows scaling (125%, 150%) and Mac Retina displays enlarge the screen to make text bigger. So you multiply the logical resolution the browser reports (e.g. 1536×864) by the scale (DPR) to get the actual monitor resolution (1920×1080).
Refresh rate (Hz)
How many times per second the screen redraws. Standard monitors are 60Hz, gaming monitors 144–240Hz. If a gaming monitor shows 60Hz, check the refresh rate in Windows display settings.