As someone from East EU, this is actually plausibly accidental, though the timeline is suspicious.

Mushroom foraging is cultural, you can buy foraged mushrooms in farmers markets and in general it is a fairly popular leisure activity to go foraging in the woods.

I hardly know anyone over 50 who isn’t excited for the mushroom season, sometimes people do end up picking up a death cap as it can be mistaken for a couple different edible ones at its various stages of growth, though you have to be fairly inattentive to do so. That said we treat a couple of poisonings a year in our toxicoligy ward.

People legitimately fall out of windows too. It just seems like notable Russian figures are far more prone to these accidents

Do grown adults accidentally fall out of windows though? Children and people fleeing a building on fire maybe. But the only example of an adult accidentally falling out of a window in non-suspicious circumstances I can think of is that guy who was trying to demonstrate the shatter-proof glass in his office building. Even that wasn’t really an accident, he did it on purpose.