Allays are immune to several types of damage due to natural regeneration

In 22w15a, allays were given a natural health regeneration of 2 health points per second, which (possibly intentionally) makes them unable to die to most types of damage, including fire, cactus, drowning, freezing, suffocating, punching. etc.

How to reproduce:

1. Trap an allay somewhere where they take passive damage of 1 or 2 health per second.
2. Observe.