Version
Minecraft: Server/Client 1.17.1
NBT Crafting 2.0.22

Description
[Demo]

To Reproduce

1. Install only Fabric 0.11.6 and NBT Crafting
2. Run vanilla server
3. Try to join
4. Get disconnect

Log
Absolutely normal.

Well, that was never meant to work.

Nbt Crafting is a mod that is designed to run server side only and provides some visual additions and fixes for the client.

Therefor:

Client: Optional
Server: Required

If you want to join a vanilla-ish server then you'll have to remove Nbt Crafting on the client end.

Ok...