Obviously I don't really know the truth anymore than you do but since Hamas deny doing it in response to the killing of an Iranian general, it seems ridiculous to consider that Hamas care one whit about that general. Note that Iran and the IRG have not weighed in on Hamas' side in this war. Nor has Hezbollah beyond a few skirmishes but nothing close to what they are capable of. Hamas' allies are in the Sunni world, not Shia. If it were true, why would Hamas hide that? It would not have been a secret for a start, they would have proclaimed that at the time.