How to replicate: place any item in crafting table and take it out. Voila! You now can receive your free copper to silver upgrade. Checked it in REI; it appears that it is a blank recipe that still results in item being craftable every time.

This issue is now fixed in the upcoming 1.17.1 update

Thank you for the bug report! After some testing it seems this happens when you use Iron Chests without a mod that includes copper or silver ingots. I did some investigating and this is unfortunately a bug with Fabric and CottonResources. I have submitted a bug report to the developer and hope to hear back soon. Unfortunately this seems out of my hands for rn :(

Okay, thanks for responding, hope CR dev fixes it soon!