I have curios installed and the keybind is not working. It appears in the tooltip but only lets me use the backpack by holding and right clicking

Sorry, just realized keybind does work, but only when the backpack is in my hand, which is the same as right clicking. So the issue is when it’s in the curios slot

Sorry, I feel stupid again. The issue is definitely the curious slot. I can have the backpack anywhere in the inventory and keybind works.

Curios wasn't released yet when I updated Packed Up to 1.17, so it's compatibility (with the keybind) is currently disabled.
I guess I will have to update it then 😅

I enabled the Curios support again in Packed Up 1.0.23a for 1.17 now.

Thank you for reporting the issue!