I have knowledge of this sort of vandalism at non-SF events in the 1980s and 1970s. And of course such things have happened before. So it's not unknown beforehand - Shriner conventions used to be infamous specifically for things like hotel damage, for example.

I don't really know if there's a trend, because I lack real data, but the vandalism-to-hotels damage is not something I've seen associated with F&SF cons, historically. I imagine it, like so many other things, is cyclical - but that means you need to get ahead of it to blunt any surge, and reinforce that "you do not. fucking. do. this."