I was testing to see if another bug happened in the newest snapshot (MC-89106), when I found out I couldn't actually do so because the ender dragon kept regenerating, even though I had destroyed all the ender crystals.

There was nothing indicating where the ender dragon was regenerating from, and it would regenerate no matter where I hit it.

I also noticed that the ender crystal itself was missing from 2 areas with iron bars around them, but even though I destroyed the bedrock this would still happen.