Since apparently sometime in the 1.14 snapshots, summoning the enderdragon with end crystals results in blocks which are in the way of the crystal beams getting destroyed, see attached videos for demonstration, and here for a larger version: https://youtu.be/oViSZ26G-ew
This is valid for any block "in the way" of the crystal beams, it can be of course also e.g. bedrock.
It seems that the obsidian pillars generate differently than before, thus the crystals are off-target, their beams are offset, and thus can "chomp" those obsidian pillars or any blocks which are in their way (e.g. also the iron fences).
1.13.2 (left) vs. 18w50a (right)