So it does look to me like this is the same bug, as I have definitely confirmed that this happens at y=63. To add to MCPE-168518, the chests do not need to be double chests, and placing blocks is also a trigger. Additionally I have found that if the chests are supported by a solid block the damage does not trigger. The damage only happens if the chests are floating. This would indicate that the game thinks the player is repeatedly falling and hitting the chests, and support the fall damage theory of MCPE-168518.
hatchface3000
REALMS-11600
So it does look to me like this is the same bug, as I have definitely confirmed that this happens at y=63. To add to
MCPE-168518, the chests do not need to be double chests, and placing blocks is also a trigger. Additionally I have found that if the chests are supported by a solid block the damage does not trigger. The damage only happens if the chests are floating. This would indicate that the game thinks the player is repeatedly falling and hitting the chests, and support the fall damage theory ofMCPE-168518.