An ancient plugin is running in legacy mode
Applies to Paper, Vanilla.
What it looks like in your log
Legacy plugin MyPlugin does not specify an api-version.
What causes it
A plugin without an api-version declaration was written for Minecraft 1.12 or older. The server shims it, but breakage is common on modern versions.
How to fix it
Look for a maintained fork or a modern replacement. Legacy plugins are the first suspects when items or blocks misbehave.
Not sure this is your problem? Paste your log and Roastd will tell you which of these it actually matched, and what else it found.
Check your own log