Pushing with a piston with destroyable blocks that is outside of the world border activates the piston

The bug

If you place a budding amethyst, then reduce the world border so that the amethyst is just outside the border, and you activate a piston (that is in the world border) to push at the amethyst, the piston activates, breaking the amethyst, and retracting the piston plays part of the animation.