Flares can remove blocks from the world.

The easiest way to reproduce this bug is to put the player inside a block, so they are suffocating. If they throw a flare, the block they were obstructed by gets deleted from the world.

It is not required for the player to be inside a block though. Simply spamming tons of flares at any block will eventually destroy the block. This is especially common for blocks with small hitboxes, like torches, glass panes or chests.

Version 1.3.3.