When an explosion occurs, if it damages blocks outside the vanilla heights (0-255) they stay unchanged.

Steps to replicate:

• Create a world with heighs under 0
• Go to below 0
• Execute /summon tnt
• The nearby blocks will remain unaffected

Expected behaviour:

• When the tnt explodes, the neaby blocks should be destroyed

 I have attached a datapack that generates a custom overworld with moddified heights.

I have identified the cause of the issue and have already a working patch that fixes it. I will open a PR as soon as I can and link it here.