After the initial enderdragon, subsequent dragons spawned using clay do not display any sort of health bar, making fighting them somewhat guesswork.
Linked issues
Comments
[Mod] Neko
Ezekiel
Duplicate of MC-83239 – If you have not, please use the search function in the future, to see if your bug has already been submitted.
Dupe of MC-83239
Already fixed for future snapshot.