Historical Rules · 8 July 2022
Rule 406.5
Official source text from the 8 July 2022 Rules release
Exiled cards that might return to the battlefield or any other zone should be kept in separate piles to keep track of their respective ways of returning. Exiled cards that may have an impact on the game due to their own abilities (such as cards with haunt) or the abilities of the cards that exiled them should likewise be kept in separate piles.