Summary:
Respawning the enderdragon causes the cages around the endcrystals (on the pillars) to explode. When the previous end crystal was not destroyed.

Steps to reproduce:

• Create new world (Creative, seed 1248 was used)
• Go to the end (/setblock ~ ~ ~ end_portal)
• Kill the ender_dragon /kill @e [type=ender_dragon]
• Use end_crystals to resummon the ender dragon (/give @s end_crystal)
  (Place the end_crystals on the platform in the 4 corners to respawn the dragon)
• Carefully watch the towers that have cages around the end_crystals

Observed behavior:
The (iron bars) cages around the end crystals explode and only the lowest ring (of iron bars) remains

Expected behavior:
The cages around the end crystals are regenerated when respawning the ender dragon during the respawn sequence (and do not blow up).

Video attached:
Minecraft 2019-10-09 13-16-29 clip.mp4 NEW 1.13.0.18
Minecraft 2019-09-25 19-36-17_Trim.mp4 (old)

Notes:
If you do /kill @e you possibly removed the end_crystals and the bug might not appear.