Some packs may contain older, less desirable sets
Foil $472 .
So if you really want to know what promos are Pauper legal, you have to find a list of all common Magic Online promos then MANUALLY LOOK UP EACH CARD to see if it has other online printings (in which case it isn't legal), unless one of those other printings is at Common (in which case it is legal)
It'd be a big smack in the face to see the versions of Captain America and Black Panther we already have as the face commanders of these new decks, but that's super unlikely to happen, and those cards might still appear in the 99 of their respective decks, or even in the main set or an associated bonus sheet
It's a tricky mechanic to deal with, indeed
I think until Cutter loses its grip on the format (which might not be for a long time) you can relegate this one to your trade binder, but I might keep it around just in case