Issue with cracks on geometry

I have an issue with a 3d model I just uploaded. Here is the link: Ιερά Μονή Αγίου Ιωάννη Βαζελώνος - 3D model by George Agelis (@bassistas) [239f4e0] - Sketchfab
There are a lot of cracks everywhere and it looks like as the polygons are shifted from their original place. If I zoom in close enough I can see also there is a gap between these polygons. The model looks perfect in metashape or in 3dsmax. This issue appears only when I upload the file to sketchfab. It seems that its something related to the textures as I see the cracks appear according to the UVs in the model inspector but I tried a lot of different formats, polygon count and texture sizes and it still does the same.
Any suggestions?

I’ve seen similar issues with vertices getting a tiny bit displaced. I’ve been told it’s because of the quantization applied in Sketchfab’s processing for vertex compression.

In your case I think the crack issue must appear because your model is partly made of loose sections that have overlapping double vertices that aren’t acctually merged, and therefore are able come apart a tiny bit when uploaded.

If you in your modeling program apply something like “Merge Vertex by Distance” on the entire model and using just a tiny Distance Threshold, It should merge those overlapping double vertices, and thus prevent the model from being able to crack apart like that.

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