The bug can be reproduced like this:
Place a 3x3 wall using any lightblocking fullblocks
Break the middle one
Put / spawn a parrot in it
After reentering the world I've played, this problem still occurs.
I haven't used any add-ons for this world. Here is the link for my world:
https://drive.google.com/file/d/1LmRIzYHprF4hq0tvRNxyVaj9iHcEZ1Nu/view?usp=drivesdk
I have to rename them
yes it was
Can confirm in 1.20.12