macOS suddenly exhibits weird mouse acceleration after idling Not sure what changed in the system but I'm running 10.15.6 (19G2021) and suddenly it have the mouse acceleration really fast if the system is idle for a few minutes.
As soon as I move the mouse for 1 second, the acceleration does return to normal.
I have a custom acceleration set in this system like this
defaults read .GlobalPreferences com.apple.mouse.scaling 0.125

Not sure if that matters.
I also have a Logitech mouse that is controlled by their software GHub.
I've had similar issues with a Logitech MX2 &amp; Logi Options.
My bet is the Logi controller that 'forgets' what it's doing.
Tests would include:-

uninstalling their drivers &amp; see if the same happens without;
test a different mouse;
see if your G-series can be used fully with something like SteerMouse or USB Overdrive.