About Heart Recovery

I always enjoy playing MineCraft. Since yesterday when I was playing, my heart recovery has stopped at 0.5 from the maximum value, and I am now in a situation where I can't recover to the maximum value. I died once and fully recovered, but after taking damage, my heart recovery stopped again at 0.5 from the maximum value. I didn't know what to do, so I'm reporting it. Thank you in advance.