It’s a massive, massive red flag when someone goes the “Terran Empire/Section 31 did nothing wrong” route.
It’s very common in zone chat on Star Trek Online. Some fascists just hang around Earth Spacedock all day there, posting nonstop fascist screeds, and if they’re ever actually out in their ships, without fail it’s “ISS” prefix with names like “AYN RAND.”
Disclaimer: Yes some people play bad guys in their games, but I don’t think just playing the part involves hours-long rants about why the (slurs here) need to be wiped out in zone chats.
EDIT: I think I’ll add “fervent Discovery apologists, especially ones that stan for space fascists after contrived apology arcs,” if only because of their repeated tendency to feel very smart to the point of undue arrogance about contrived “what if mass murdering dictators… actually good once the protagonist buddies up with them?” bad writing cliches.