Allays naturally regenerate 2 point heart per second in Java Edtion if damaged, or 1.83 point heart per second in Bedrock Edition.

It's a vanilla parity issue.

How to reproduce:

1. Create a allay cage
2. Put a allay into it.
3. Observe if the allay will die.

Expect results:

Allay will not die.

Observed results:

Allay will die after 200-240 times damage.