[Apple M1, v3.61] Viewport goes NUTS when editing curves

Hey! I have a bizarre bug which occurs when editing curves.

In Edit Mode with a curve object, my screen decides to go on an acid trip, an annoying problem when tons of visual artifacts clutter and dance/move across the viewport whilst trying to work.

It doesn't happen when I switch "Show Overlays" off.

Picture and video below. Help much appreciated!