ZBrushCentral

Having an issue in terms of texture painting

ASs

As a new comer in this software Zbrush, I’m trying some features.
In this case, texture painting.

I turned everything off except for rgb, started painting on it
Then I saw square remnants of strokes every time I paint on an object

although this doesn’t last forever once I move my view,
it happens when I paint again.

I have no clue what’s wrong