This bug only happens if the client ask you to choose a card to be discarded, then there is an additional confirmation prompt before you discard the card. So not all cards with similar effects have the bug.
If you decides to choose the adventure side, effects that cares about type of card being discarded (for example Strongarm Tactics)
From Bug Blog.
Bug Blog Text: Adventure cards incorrectly display that you may discard either the Adventure or the creature to an effect such as [Smallpox].
This bug only happens if the client ask you to choose a card to be discarded, then there is an additional confirmation prompt before you discard the card. So not all cards with similar effects have the bug.
If you decides to choose the adventure side, effects that cares about type of card being discarded (for example Strongarm Tactics)
From Bug Blog. Bug Blog Text: Adventure cards incorrectly display that you may discard either the Adventure or the creature to an effect such as [Smallpox].
Screenshot
Affects: [Smallpox], [Creeping Dread], [Miasmic Mummy], [Rotting Rats], [Stronghold Rats], [Sibsig Icebreakers], [Strongarm Tactics], [Earsplitting Rats], [Cunning Lethemancer], [Mindlash Sliver]