Artifacting... it's getting worse. (Patreon)

On the top is a render from Iray in Painter.  On the bottom is the Iray render from DAZ (both render and Iray Preview).

Going back to how I got here, I was asked to make some new textures for one of my older Genesis 2 Female items.  For the life of me, I couldn't find the Painter file for it.

I reconstructed the SPP from existing normal maps and such but though ... "this UV map really sucks."  It had gaps and so on.

So, I ended up redoing the UV map but the more I looked at the mesh the more it needed to be fixed too.

All fine to this point, but once I exported out SOME textures from Painter, I noticed some artifacting in DAZ studio renders.

I started to turn off channels: roughness, metallic and then the base colour.

Seems that it's caused by the base colour channel.

The next thing I do is go and look at the exported PNG file from Painter.  I don't see anything that could cause it in Mac Finder/Preview or in Krita.  .

I go back into Painter and use Preview mode to see if the artifacting is there too.  It's not.

If I had to guess, it's some sort of compression artifact once the textures are loaded into video card memory.  

Even more confusing is that it doesn't happen to all textures too.  Wondering if it's caused on textures where you have a lot of one colour and then once it transitions to another colour, it generates these box outlines.

I made other designs that don't seem to have this issue, like my regular tiger print one.  It also transitions from a solid colour to solid black and no issues at the boundary.

I also thought that because I use passthrough paint layers to get rid of seams, that might be causing the issue somehow but disabling them for DAZ didn't resolve it.

Updated:

It just gets worse.  I even tried to export at 8192 x 8192 but it has no effect.

It may seem counterintuitive but when I reduced the sizes down to 512x512, a lot of this stuff disappeared, but not all.  All the distortions and bleed on the trunks part went away, but the colour bleed on the waistband logo remains.

I figured that if the textures were too large, then the textures would be compressed before sent to the video card and this compression was causing the problems.