Unity 2019.3.0.f3 How to reproduce: 1. Create a new 2D project. 2. Create a square sprite and drag it to the scene 3 times, with different positions. 3. Make one square parent of the other two squares. 4. Write a script for one of the children, and set its parent as null on Start(); 5. Enter play mode, drag both children in & out, the one which set its parent as null would rotate weirdly.