While mining a block, if the tool is repaired, the block-break progress is reset

While mining, if your tool is repaired through any means (most common being mending but mod enchants that do auto repair are also affected) the block you’re currently breaking is reset back to full unbrokenness.

This can get very annoying in certain circumstances since auto tool repair can make mining out affected areas take way longer than they should since the block breaking progression gets reset constantly.