Relates to MC-270322.
Steps to Reproduce:
Place a heavy core
Use
/effect @s haste 30 255
command to get haste statusMine heavy core without pickaxe
Observed Results:
Heavy core drops.
Expected Results:
Heavy core should not drop.
Comments

Thank you for your report!
However, this issue is Working as Intended.
The report you have submitted is working as intended: heavy core is supposed to drop itself when mined with any tool.
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Can confirm, relates to MCPE-180441.
This could be intended, the 1.21.0.20 changelog only states that pickaxe is theΒ preferred tool of heavy core.