Heads up for an appearance collectors:
Say you are like me and have all your reputations unlocked on a single character (just as an example, a human because previously it made reputations easier to farm).
Or say that you have reputations maxed on a character, but there is an appearance that was attached to that reputation that your character couldn’t learn.
One effect of the changes to transmogs being neither bound by class or armor type is that you can now collect every transmog appearance from every reputation on a single character. So if you are like me and have a bunch of old reps you did years ago before the transmog changes, you will want to go back to each of the reputation vendors and select show all items on each of those vendors since they probably have appearances for other gear types than the character you farmed that reputation on.
This is also true of the legacy pvp and BFA faction-specific vendors, though with the obvious caveat that most pvp appearances are faction-locked still. that said I know for at least bfa and potentially many other legacy reps that are faction-locked when I bought the appearance on alliance it showed me unlocking the horde equivalent appearance. Not sure how many pvp appearances work that way though, nor if buying a faction swap on a character with a lot of alliance or horde alts will unlock the equivalent appearances when they faction/race swap.
Also if/when older reputations are account-wide, this will be a lot easier since rep will be shared across characters. But since some reputations will still likely be character-specific based on the exception for account-wide rep when it came to dragonflight , its worth getting started on going through any older reps you have and seeing if they have any appearances you are after and which character you have on your account that has that reputation maxed. Its also worth making sure in future if you get an old reputation to max to check if appearances from classes besides the one you farmed the rep on are ones you want, since by default the old reputation vendor UI will only show appearances for the class your character is.
Some suggestions for bliz when they go back and make older reps account wide:
A huge quality of life would be if you make a single vendor(say chromie, or that npc that sells all the tabards from every reputation) that allows you to buy any appearance from any previous reputation that you have exalted on your account. Currently there are over 100 reputations with appearances, and to even get to the vendors across the game can require flying to most of the zones of the game. In ffxiv and similar MMOs, there are legacy vendors that just sell all the old appearances and cosmetics in 1 place, saving you having to go exploring literally the entire map to find the vendors with appearances.
Another, simpler option, would be simply to allow any appearances that cost trivial amounts of gold to automatically unlock as appearances when you are exalted at least once on at least 1 character in your warband.