Annoys the bejeesus out of me too, someone needs to make an addon or weakaura, I need my cursor blink back
To my knowledge though you can’t hide the mouse cursor so I don’t think there is a way to make it “blink”
Several other threads on it
https://us.forums.blizzard.com/en/wow/t/mouse-click-cursor-not-disappearing/690145
https://us.forums.blizzard.com/en/wow/t/right-and-left-click-pointer-bug/676147
https://us.forums.blizzard.com/en/wow/t/stationary-mouse-click-no-longer-hides-your-cursor/616695
https://us.forums.blizzard.com/en/wow/t/alright-hold-up/679362
https://us.forums.blizzard.com/en/wow/t/bug-stationary-cursor-does-not-hide-on-click/645352