How about adding skills?
Each Crewmate and Impostor will be given 1 skill randomly every round from a pool of 50 available skills. The skills can be helpful or disadvantageous, or straight up making you sus.
Each skill will have different cooldown durations, except passives which permanently active.
For Impostors, their kill cooldown will reset if they use their skill and vice versa. This way, the Impostors cannot use both skill and kill at the same time.
Example of skills I came up with:
Decoy - leaving a clone behind which can be killed by the impostor, but leaving no dead body behind.
Engineer - instantly finish the closest task. Cannot fix sabotaged rooms.
Remote - [passive] Can interact with anything at longer distance.
Reinforce - prevents selected room from being sabotaged for x seconds.
Puddle - drop a slippery puddle behind you. Anyone walked over it will have sliding effect for x seconds and removes the puddle.
Kill Button - a replica of the kill action the impostor has. Upon using it, the target will get the kill animation pop up but not actually killed.
Blindfold - [passive] anyone near you will have their screen turned black.
I may be able to help in brainstorming other skills if the devs like this idea.