21 is just a by product of horaces quests to max affinity. 22 is horaces favourite underwear which is once you reach max affinity.
And with 22 you don't have to buy back from the bandit if I remember correctly
Viewing post in Underwear Help
Nah, 21 is Horace's favorite underwear and you get it automatically. The 22 you get during his 2nd(?) heart event but you have to buy it from the bandit. There is no announcement that it is available annoyingly enough.
Or the numbers are reversed. Either way, you have to buy it and there is nothing to indicate that.