Has anyone came across a checker pattern similar to this when doing tumblers?

The image attached is just a square set to fill but it comes out looking like a checkered pattern. Any ideas what could cause this or had anyone encountered this before? My only thoughts are consistent drops in power at each spot where the paint was left. It’s odd because there seems to be a very specific and accurate issue that’s causing the pattern to be identical all the way up the square when filling. Crosshatch wasn’t used and I did the tumbler with a 0 degree scan angle so it may look crosshatched but is not. The black lines are paint not metal burn. I’m also running a diode laser that’s on 10w mode(10/20w laser module). I can get a clean engraving but that isn’t what this post is about. I’m just looking for what would cause this.