Most do! Even the worst filters. It's kind of the logic behind them, non exclusive to this game.
"iscord" catches Discord discord (D)iscord etc
If we had regex we could do *iscord to catch all of that and things like Biscord or Criscord, whereas ?iscord would only catch Biscord and Discord but not Criscord and (D)iscord etc.
But we don't have regex so you'll have to settle for creative things like iscord and .co