When the Decorated Pot is copied from the world (as a block with the pick block key (middle click by default, without pressing ctrl) to the hand in creative mode, the pot in the hand will contain the items that were in it the Block wich was copied.

How to reproduce:

1. Place a Decorated Pot and put a few items in it
2. Pick the Decorated Pot in creative mode with the pick block button (middle click by default, you will notice that the pot appears in a different slot)
3. Run the following Command to check the content:

   /data get entity @s SelectedItem

Expected Behavior:
The output is:

<Player> has the following entity data: {components: {"minecraft:container": []}, count: 1, id: "minecraft:decorated_pot"}

Observed Behavior:
The output is (with 4 potatoes and inventory slot 0 as example):

<Player> has the following entity data: {components: {"minecraft:container": [{item: {count: 4, id: "minecraft:potato"}, slot: 0}]}, count: 3, id: "minecraft:decorated_pot"}

This bug is very similar to MC-273960. (Perhaps it was created as a result of the bug fix)