I saw reports of clubs aware that it happened to them but they considered the case closed. If they have proof and they see what the punishment is, you've got to imagine they'd consider it...
I have no knowledge of why they've come to the decision but I would assume the EFL's rationale is that the play-offs is a separate competition (i.e. knockouts), so we forfeit our position for spying ahead of the 1st leg.
Have the EFL rushed this on purpose, knowing we'd win the appeal? They'd then be able to come out against us strongly for putting the fixture – and wider game – into disrepute.