Basically, when I set the attribute 'generic.max_health' to my character with any number (in this case 6) other than 20 while having regeneration effect and exiting via the exit portal, my health will start increasing until it reaches its initial health which is 20. Even when quitting the world and joining back, my health still increases. While this is occuring, my health will also start flicking back to 6 unexpectedly and continue increasing. This bug happens only when exiting the end dimension, I have tried the nether portal and it did nothing.
(See attachment)
Duplicate of MC-181604.