To prevent mesh distortion when parent objects are rotated, it is essential to maintain a uniform scale on all container objects within the hierarchy.

1. Identify the parent GameObject causing the distortion by checking its Transform values for any non-uniform scale (e.g., scale values that are not identical across X, Y, and Z).
2. Reset the parent’s scale to a uniform value, preferably (1, 1, 1), to ensure a clean coordinate system.
3. Apply the required non-uniform scale only to leaf nodes, which are GameObject instances that do not contain any children.
4. For rotational components like turrets or hinges, create an empty GameObject to act as a pivot. Ensure this pivot has a scale of (1, 1, 1).
5. Parent your mesh to this pivot and modify the Transform.localRotation of the pivot rather than the scaled mesh directly.

Additional Tips

• Bake your non-uniform scale directly into the mesh using external 3D modeling software or ProBuilder before importing to avoid runtime hierarchy issues.
• If you must scale a parent dynamically, ensure all children are unparented before the rotation occurs and reparented afterward, though this is rarely performant.
• Use Transform.lossyScale in your script if you need to read the global scale of a mesh affected by a non-uniform scale higher in the hierarchy.