Might just be confirmation bias, but I do agree that plague unfortunately has an above average percentage of people that are immature (e.g. Ils/Eviscerate, Luvia, people involved in the WvP drama). I wonder if the edgy aesthetic has to play--I've always felt that people who lean into being edgelords also tend to be a bit childish at times.

Alternatively, maybe there's nothing special about plague and it's just that being the third largest flight results in a larger raw number of clowns (even if the proportion of clowns is the same as the other flights).