Zac always comes back from passive, even if all blobs are destroyed

Whenever Zac's passive is activated, if all the blobs are destroyed, he immediately comes back with roughly 1hp. Obviously he should die, but that doesn't seem to be the case right now. I attached a video that shows the passive going off, a tower killing all of the blobs, and then me coming back to life after the final blob is destroyed.

I have seen it happen from champion last hits, and minion/monster last hits, so it is not just from towers, I just didn't get recordings of those.