Drawing a black line, and little white bits show up in it

Hello, I am using Elements 2021.

Lately it happens very often that when I draw something in black, there are little white spots in it.

example

Now I apologize for this horrid drawing, this is very tiny in the actual image so there's a severe lack of detail and proper anatomy.  And it is very dark so I brightened it a bit, making it look even worse.  But you see easily the white spots.

I can fix this by locking the layer and just painting black over it again.  But I don't know why it happens in the first place, it's kind of annoying and it was never a problem before, I have obviously had the program for years (and older versions before that, I've been using elements since around 2006).  It weirdly happens only with line art like this, not with coloring larger areas.

I realize it's a shot in the dark but I was wondering if anyone else has this problem, or if anyone would know how to make it stop.