• game version: 1.20.1 fabric
• mods involved:
  • accessories
  • trinket-compat-layer
  • l2hostility-fabricated

Ah yes this is a known issue solved within 1.21.1 but has not been backported for 1.20.1 as there is a difference between the API check for canEquip that leads to issues where the trinket item checks itself again for being able to be equipped but finds it self and just sees it as a duplicate stack.

This line here is the cause in a sense with how Accessories and Trinkets differs. Frankly in most cases this will not be fixed as 1.20.1 support from now on has been dropped in favor with keeping up with Minecraft updates and targeting 1.21.1 for the moment.

Support for 1.20.1 is being dropped and I recommend investigating if the issue exists with this mod on 1.21.1 if possible with either reopening this issue or creating a new one.