So, I just noticed on rewatch that 17's wish was "Please restore all of the universes that were erased."

So keep in mind that, originally, there were 18 universes, and Zeno has already erased 6 of them. Possibly for very good reasons.

The way 17 worded that wish, those other 6 universes should also have been restored.

What Zamasu-level evils that had to have their entire universes erased to stop them might 17 have unleashed on the multiverse?