Cubik Studio

So I noticed this shadow on my textures as seen in the pictures. It's almost like the game wants to make the shadow more compact for some reason or fit the whole shadow in the narrow area. Now I have no idea if this is an ingame problem or if I messed something up while making the models. It can be fixed by removing shadows in studio, but i just wanted to know if there is some other solution. Sorry if this is a frequently asked question.

I never seen that issue before and not sure how to fix that but it looks like a common light/shadow bug with the Minecraft smooth light engine.
You can try disabling Ambient Occlusion for your model or disable shading for those specific elements and re-export