Latest days the server has been randomly crashing for some reasons. It might have to do something about the "End of the Line" update.

It's because of the unusual effects donors can apply to weapons, some make everyone on the server crash.

I'll try making a list for frog.

Doesn't seem that the server has been crashing. So it's a client crash, yes? If so, then it's something Valve need to sort out.

How did you deduce, or what makes you think, that it's the unusual effects that are the cause?

To test out your theory, unusual effects on weapons have been disabled after the first map change after this post.

Don't think it has anything to with the unusual weapons. It happens sometimes when the boss dies and MeeM cause players from time to time when he's being played. I think it has to do something about the ducks in the latest Major update.

If certain effects are applied to certain weapons, every client connected to the server crashes as soon as the weapon is taken out. Off the top of my head I can only think of one example; Gunslinger with either Vivid plasma or Green energy, I'm not sure which one (not even sure if it's one of those effects, I'm positive the gunslinger is affected tho).
When I first got donor I messed around with the effects on my engie weapons on a late night session and managed to make the few people on the server crash, multiple times. Oddly enough it only happens with certain combinations.

I thought it was a known problem considering the donors I've mentioned it to already knew about it

Well apparently it's not the unusual effects that cause all the crashing.

I'm still certain that the unusual effects can make everyone on the server crash.