Description
Placing a backpack will become another backpack of specific type when placed facing a direction however only on an Aternos server

To Reproduce
Steps to reproduce the behaviour:

1. place backpack on a block.
2. backpack should snap into a block position and become a different version to what its item was.
   *note: if replicated in single player bug is non existent
3. leave server
4. come back into the server and any placed ocelot, cow, pig, chicken & villager back pack will disappear any other backpack will remain

What should happen
The backpack should be the placed item version, the same as the item's version in an inventory

Screenshots
Image 1-3 on shows a backpack placed facing East and image 4-6 shows a backpack placed facing South. Image 7 is after I left the server to replicate on a single player world which had no error on return, the backpacks vanished. (placing a backpack whilst facing North and West will flip the backpack) and last image shows the mods on the server

Other info

• Mod version: 1.16.5 Curse forge version (36.2.0)
• This is on aternos server

Additional info

Update to 5.4.6, and check if issue still persists

Any updates on issue?