It's actually just cursor latency specific to the windowed environment you're running. From what I've experienced (with a 4060 Ti) it doesn't seem to impact FPS games at all.

I haven't tried any games that use a cursor with Wayland yet so I don't know if it would have an impact there.

I think it has to do with whether or not the game in question is reading the mouse device directly (e.g. through SSL) or via the compositor. If it's reading the device directly it stands to reason that there would be less latency.