Question White grid showing on single colour material

I'm very new to Unity, haven't started looking into how lighting works yet. I did try baking the lights though.

Maybe I'm doing single colour materials wrong, I tried setting the albedo colour only and using the roughness / metallic sliders to adjust the look. There's some strange grid patterns that are appearing on my object though. The grid doesn't align with the 3D mesh, and it all looks good in Blender.

I created a dummy Unity project to work on my 3D modeling / material creation skills, basically everything is default settings. I decided to see what my assets look like with a single colour type of look.



Those rocks are the same model. Any ideas how to get rid of those grid lines?