Self harm(?) Without stimulation

I have noticed that when I'm in a situation that isn't very stimulating (sitting in a meeting, on a zoom call, etc), I will dig my nails into my arms without realizing at first. When I do notice it is very hard to stop because something feels wrong or strange when I dont do it. Is this self harm, and does anyone know why I impulsively do it (and how to stop)?

If it's important to know, I do have strong depression, but don't often feel anxious or have an anxiety disorder.

Thank you for your help.