@GooUckd opened this Issue on July 7th 2021

In 1.17.1, PhoenixSC discovered an anvil glitch that can duplicate items. This could be exploited via automation (?) or some other help that can for example, fake the inventory being full or increasing the chance for the anvil to break.

The video:

@Cyberspace999 commented on July 27th 2021

Pretty sure it's been patched,