I thought I had a solution. I was wrong.
I swicthed the normal map to a bump in the sketchfab editor and saved the changes and viewed the model. It defaulted back to a normal map but looked much cleaner.
I also reuploaded the normal map as a .png instead of a .jpg this also corrected the display issue.
I tried switching the texture in the skecthfab editor from trilinear to nearest mipmap. Which has had the best results so far.
So after viewing these changes in multiple browsers from multiple systems, it fixed the issue for about 10 minutes. Then the texture defaulted back to looking worse than before… I’ve tested this three times now and was able to repeat this bug. I don’t understand why it shows up good for a short period then defaults back to a low quality.
Update, I uploaded a directx normal map and it seems to be working. On the different browsers and devices. without the horrific artifacting. We will see if it defaults back to low quality again but, I’m feeling optimistic.
Update, After about a 15 minute wait no luck. The texturel has defaulted back to very low quality.
So I think the only solution at this point is to break the model up into more uvmaps to increase the texel density.