Hey guys! So something I found out through a bunch of frustrating trial and error was this: https://forum.allegorithmic.com/index.php?topic=18330.new#new I had horrendous, different lighting between a specific set of UV islands on my shield I uploaded, and couldn't figure out why. After restructuring my UVs, it seemed to have come down to flipped UV islands in 3DS Max. In Substance Painter the textures looked fine, but in Sketchfab the lighting on ONLY the UV islands that had been flipped goes haywire. Anyone know why this might be?
photos can be found in the link to the forum post I listed above