I guessed "transgender", but the actual answer is quite encouraging

surprise!

“The most common red flag for men — with nearly two-thirds agreeing — is if a partner identifies as a communist, according to a Change Research survey published in September.

That makes sense: who wants to spend time with a hysterical, shrieking idiot? But the next revelation doesn’t bode well for future boy/girl relationships, and I’d expect to see “irreconcilable differences” as a leading cause of divorce in the years ahead, if there even are any marriages.

“For women, with more than three-quarters agreeing, identifying as a “MAGA Republican” was the top red flag.”