(EDIT: FIXED LINK)
The creaking mob moves while the player is looking at it through the hanging moss, even though the line of sight isn't broken. This behavior was most consistently seen while the player is jumping or crouching repeatedly. The creaking mob also was sometimes sliding slowly without playing a walking animation and attacked while the player was looking at it through the moss while jumping/crouching. I have attached a txt file with the link, as well as inserting the link directly in this bug report, to the Google Drive folder with the footage.

How to reproduce: Go to a Pale Garden biome and a naturally spawning creaking mob (I do not know if the creaking must be naturally spawning for this bug to be seen. Same thing with being in the Pale Garden biome) and place hanging moss between you and the creaking. Go to survival and press crouch and/or jump repeatedly (I had a leaf blocks right above my head, but I do not know if this affects the unwanted creaking behavior) and maintain line of sight with the creaking. The creaking should move, even though you are looking at it.

Google Drive Folder link \/

https://drive.google.com/drive/folders/10n-4pXAU4I5bWadL1v0XaT9Q8neX_fjE?usp=drive_link