this is the version I used
(Fabric 1.20.4, traveler's backpack version 9.4.4)

1. Describe the bug
   When you place a backpack with any nbt data on it into a trinket slot, all nbt data gets deleted, deleting all the items inside the backpack.

2. Write steps to reproduce the bug
   get a standard traveler's backpack with a backpack tier of netherite and place it into a trinket slot. the backpack should turn into a leather tier backpack.

3. What is expected behaviour
   Not deleting any data

4. Screenshots (If applicable)
   

it works now, thanks

I also tried it with nothing but travelers backpack and trinkets but it also did the same thing.
also another thing i forgot to mention is that i am on quilt. I highly doubt this is a quilt only issue so im not going to try it

Update trinkets to latest version for Fabric 1.20.4