Unwanted shadowing

Hi, forgive me as an amateur! But can anyone explain what might cause this strange shadowing?

This is the matcap image which then effects any texture I add in a lit scene in sketchfab, any help appreciated!

Many thanks

Can you share a link to the model please?

Sure - Book box - 3D model by chrisuon [76acdda] - Sketchfab

Hmm, it looks like you may have set that side of the model to smooth shading in Blender. Can you try setting the entire model to flat shading and re-uploading?

https://docs.blender.org/manual/en/latest/modeling/meshes/editing/face/shading.html

Yes, that has removed it, thanks!

If I want to use smooth shading is there anyway to avoid it happening?

You could try subdividing the object before uploading. In general, smooth shading gives unexpected results on low-poly models.

I will do some experimenting, thanks a lot for your help!

beveling edges will in problem areas works a lot of the time