If a mob is affected with health boost (any level) and has health over the normal amount, its health will be reset back to the normal amount for that mob when the player relogs. The health boost effect isn't lost, but the hp of the mob is just reset back to the default amount.

Steps to Reproduce:

1. Spawn a mob
2. Effect them with a high level of health boost using commands
3. Throw lots of healing potions on the mob
4. Hit with a netherite sword (notice it doesn't die)
5. Leave and rejoin the world
6. Hit with a sword again

Observed Results:
The mob keeps the health boost effect, but its health gets reset back to default

Expected Results:
The mob keeps the same amount of extra hearts it was healed before relog.