I've seen it (and modded it) that icons be within five years of the character, based on how old the PB was at the time of the icons. So like ~chthonian. And I've played PB/OC and fandom so I don't see why the type of game makes a difference. It's probably a mod call, though it seems to me the other way - limiting based on current PB age - leaves players a lot less freedom, and I'm not cool with that tbh.