1 official ruling from Bandai, last ruled Jun 28, 2024. Straight answers to how this card actually resolves.

If [EX5-070]/[X Antibody Proto Form] is in this Digimon's digivolution cards, this Digimon would be deleted, and [EX5-070]/[X Antibody Proto Form]'s inherited effect places it on top of my security stack, does this Digimon's <On Deletion> effect activate?
No, it doesn’t activate. [EX5-070]/[X Antibody Proto Form]'s inherited effect will trigger/activate "when this Digimon would leave the battle area other than by one of your effects," but since [EX5-070]/[X Antibody Proto Form] isn't in this Digimon's digivolution cards at the time of activation of the <On Deletion> effect because it's placed in your security stack before this Digimon is deleted, the "if [X Antibody] was in this Digimon's digivolution cards" condition isn't met, so the effect doesn't activate.
Ruled Jun 28, 2024
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