Try this extension: https://extensions.blender.org/add-ons/mio3-uv/Udjani said:Is there any addon to traighten UV's that's not Textools or uvsquare? I think both of them started giving me bad results lately, they work like 50% of the time
Looking a lot better to me; maybe the blacks are falling a bit too black in some of the renders, but overall it feels a lot more believable to my eye~