How to fix this mesh bug?

[Zanviorus (Z4V)]

Btw when I put in dummy

[automaticcorndog (Bobbis)]

What exactly is the problem? I can’t tell from your photos.

[krasycheckz (Terrence)]

Maybe it has something to do with shading in blender.

Try enabling/disabling “Auto-Smooth” in blender under Object Properties > Normals

[DardemonX (Dardemai)]

After looking on first image I guess you can enable and disable ,double sides" in properties to fix that, but I’m sure this is the exact problem.