When a amethyst cluster moves, the game will think it is breaking (bug lasts for a tick)

Amethyst can be duped by pistons 

how to reproduce: try to get a amethyst cluster, second step: build a repeating redstone contraption that is attached to a piston with two slime blocks on it (or you can just get a sculk sensor attached to a piston) final step: activate the redstone contraption (or the sculk sensor)