Maybe more clarification is needed.
Asking someone to read off of their role card is not against the rules.The community tends to call this "metagaming", which is frowned upon but not against the rules. Anyone can memorize the role cards, or pull them up while playing.
Quoting your role card is not against the rules.Same as the point above. Anyone can pull up a role card and lie about who they are.
Posting a screenshot to prove something IS against the rules.
As stated directly in the rules which can be found in-game and at
https://www.blankmediagames.com/Rules/ :
No Cheating – Gaining an unfair advantage over players through means other than normal gameplay. This includes but isn’t limited to using multiple accounts in the same game, sharing information outside the game, using a foreign language to communicate in a way that can’t be understood by the players in the current locale, and posting screenshots to prove something happened in game.
If posting screenshots were allowed, then everyone would just do that Day 1 and the game would be over pretty quickly.