after breeding 2 horses, if you feed the baby to make it grow faster, the baby will grow up to have a few bugged hearts. it looks like it would regenerate but it never does and keeps appearing and disappearing. even if you feed that horse golden apples/ golden carrots it never regenerates the health.  it happens with literally every baby horse i feed to grow up. i have been trying to get the best horse possible in survival minecraft so i have bred those horses over 30 times. after about 5 horses i started feeding it sugar to grow up so i can quickly breed another after checking if this horse was optimal or not. since then all those horses have those bugged hearts. this bug is very easily reproducible and is really annoying. i hope it can get patched in the next update.