See the images below. In wireframe everything is fine.
Switch to shaded with edges and this happens. Why are all the circle segmented? I use shaded views constantly and now that we've upgraded to 2021 this happens. Never happened before...
For reference here are my display settings.
I don't know which setting you have where indicated below, but whichever one it is try the other one.
If that doesn't fix it, check out Why don't things look right on my screen? - CAD Forum.