Depends on what’s biologically going on

If it’s something like thrombosis and clotting it could come down to a variety of factors that made u predisposed, some u had agency over others u didn’t.

If there’s an ongoing viral reservoir then rlly idk because that’s the mechanism that seems the weirdest to me.

If it’s an autoimmune disorder or genetic disorder then it’s just predisposition snd this particular virus either triggered it by way of molecular mimicry, in which case I’m not sure the severity of infection even matters, or in some cases maybe the severity was bad enough that it wouldn’t have mattered if it was covid or influenza and it just fucked up ur immune cells, idk.