What are these? and how to avoid them!?

after i trying to scale…
my ocd cannot bear them
please how to avoid them?

Probably your scaling has moved the edges of the oval a tiny amount in the direction towards or away from the camera so that the face where the hole is is no longer perfectly flat.

how to fix it?

How to fix it?

Be careful how you scale. If you scaled the selected oval by grabbing it from a corner green handle then you are scaling in all three directions simultaneously. If you want to only scale in one or two directions use the center handle of the direction you want to scale in.