0. ALWAYS PROVIDE INFORMATION ABOUT MODLOADER (Fabric / Forge) AND MOD VERSION (For Example 1.19.2-8.2.10)
   Fabric 0.16.9,
   Minecraft 1.21.1
   Traveler's Backpack 10.1.7

1. Describe the bug
   Server mod list on my github repo - https://github.com/nar10z/minecraft-server-pc

2. Write steps to reproduce the bug
   Update mod from 10.1.3 -> 10.1.7

3. What is expected behaviour

4. Screenshots (If applicable)
   

Is you mod updated on client & server? it seems like your client is not updated

Client and server, yes

Please check again, your backpack inventory is using old texture which shouldnt be possible if you updated to latest version

Yes, after check version it's confirmed