Blizzard has commented on the recent discovery of Dragonflight ensembles being obtainable by any armor type. They note that this is currently bugged and ensemble unlocks will not be changing in Dragonflight, but cosmetic Renown unlocks will be account-wide!
Currently, there is a bug with Dragonflight vendors that are causing them to show more ensembles for sale than they should to the character viewing their wares.