Windmills Animation stretching

So I made a model in blender of a windmill and the rotor just stretches weirdly what have i done wrong?

Here u can see it


Is this a keyframe animiation or is the rotor rotating by a script? If it’s a keyframe animation does it look correctly in blender?

If it’s a keyframe animation: Weird stuff can happen if your vertex bone assignments are wrong. I once had a left shoulderpad of a character scale down as his right arm was reaching out. Check if the rotor vertices are assigned only to the rotor bone and nothing else.