Some Jokers that change their selected card, rank, or suit every round select from your deck (e.g. The Idol, Mail-In Rebate, Castle), while others choose an entirely random option (after looking on the wiki, I guess Ancient Joker is the only one). The problem is that the descriptions for both types of Joker read exactly the same, meaning there's no way for a player to figure out which is which without either rigorous testing or consulting the wiki.
To solve this issue, I think Jokers that select from your deck should be more clear that they select from your deck. One option could be "[card/rank/suit] chosen randomly from deck at end of round" instead of "[card/rank/suit] changes every round", although that might be overly wordy, so I'm open to other options.
TLDR: The Jokers that change at the end of the round should be more clear about whether they select from your deck or whethet they're entirely random.