The bug
Creakings do not have damage immunity in the traditional sense due to being impervious to traditional damage sources. However, it is still possible to make projectiles bounce off of them rather than being absorbed.
How to reproduce
Spawn a creaking_transient
Get a skeleton to shoot at it
Just before the arrow hits it, punch it
Expected results
The arrow would be harmlessly absorbed by the creaking.
Actual results
It bounces off, as though the creaking had temporary damage immunity.
Linked issues
Attachments
Comments

How is this different from MC-140857?

Creakings shouldn't have invulnerability frames.
invulnerability frame is used for other things, like sounds etc. and creaking should still have them.
Can confirm.