Prevent block variation inside certain parent blocks

A variation is a representation of the original block.

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if block-1 allows the insertion of block-2; then block-1 will except all variations of block-2.

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core/columns only allows the insertion of a core/column.

• If I create a variation of core/column I would expect the core/column to accept my variation.
• And therefor the reverse should also to be expected.

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but… block.json offers the blockHook key which might offer a workaround of sorts

"blockHooks": {
        "acme/dialog": "firstChild"
    }

P.S. This answer by Tom J Nowell goes into additional aspects and is quite enlightening