I saw
Taste the Rainbow – be in a game where Red, Orange, Yellow, Green, Blue, and Purple are the only colors alive.
The Red Spy – with 7 or more alive Crewmates, win the game as solo Impostor.
Just Getting Started – win a game on each of the maps.
Adventageous – use a vent 10,000 times.
Three Stooges – win a 3 Imposter game as Crewmate.
Wasn't Me – Win a game as Imposter without venting.
Source: https://www.reddit.com/r/AmongUs/comments/klloyi/more_achievement_ideas/