I’m at a loss on how to fix this and I can’t find an equivalent to this issue with the keywords I type into google or on this forum. The model looks smooth and as it should be in Blender.
When uploading it manually to Sketchfab, it becomes blocky, with some vertices stretched out. Could it possibly be from the use of shape keys? Do they cause exporting issues? It would be the only thing I’ve done differently compared to uploading my other models.
Edit: I’m messing with the model to see exactly where the problem lies. At first I removed the pose and the mouth shaping and everything returned to normal. Next I tried removed the shape key and kept the pose and it resulted in becoming blocky and stretching again. Also the same when I do the opposite.