Before Continuing:

• Check you are using the latest version of the mods and its dependencies
• Always include a latest.log if you are crashing
• Remove mod that enhances Minecraft: Optifine, Sodium, others. The issue persists.
• If you are unsure which mod is the culprit.
  Disable all of your mods and enable them 1-2 mods each time to isolate the culprit
• Confirm that there is no existing issue with a similar description submitted in the list of issues.

Version

1.21.1-FABRIC

Supplementaries Version

supplementaries-1.21-3.0.23-beta-fabric.jar

Moonlight Lib Version

moonlight-1.21-2.17.7-fabric.jar

Issue Detail

When I make a stack of books, and then break the stack, no matter how big it is, it only drops 1 book. I've tested this multiple times, both with normal & enchanted books — it happens each time.