When using a tool that can instant mine blocks it looks like the blocks are broken and yes they are but most of them are but some are only visually broken. If you right-click the place of the block it appears back or just relog in the world and some of the blocks appear. It's like the block lag glitch but it has an effect in single player worlds too and multiplayer is worse.

This Breaks many Afk cobblestone/stone farms. It is also very annoying when building and mining when the blocks broken before pop back