Weird behaviour when re-parenting after SetParent to null.

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.

 

Yes sir, thanks for your reply. Just send a bug report.