Hi!
I’ve noticed that when I export an SVG texture and add it to my model, I get different results based on whether I export it from Sketch or Illustrator.
Simply use use what’s best for you, the combination Illustrator/SVGOMG is clearly the less ideal. You can also increase SVGOMG’s Number Precision param and find a good compromise between file size and Texture resolution.
I’m not familiar with Illustrator but as a wild guess, I’d say it’s a resolution settings problem, reducing/optimizing the SVG file size will impact the resolution. You can also give Inkscape a try, you’ll have better controls over the final SVG especially when dealing with web graphics.