One fork in the undo is worth deciding now: how it is implemented. If it publishes a deletion event, relays are only asked to honour it. Some keep the repost, and a client that already cached it shows...
Un-repost is NIP-09 (real deletion, plus local tombstones against resurrection), show-reactions renders from the existing fetch. No second subscription, just an extra filter for non-followed overrides in the same REQ.
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