Setting entity names throws errors in 1.21

[OmerBenGera]

• [ V] This issue is not solved in a development build

Describe the bug I have a plugin that toggles on/off names of entities and items for players. The relevant code can be found here

To Reproduce Install WildStacker (b65) on a 1.21 server (I am using Paper 1.21) with ProtocolLib (b5.3.0-SNAPSHOT-723), enable names-toggle in the config file of WildStacker, then run /stacker names item while having items on ground nearby. After you toggle on/off, you'll get kicked and this error pops up in console: https://pastebin.com/kE2y3uHt I probably do something wrong, just not sure what as it worked on other versions.

Expected behavior

Screenshots

Version Info https://pastebin.com/qgC0R3f6

Additional context