My red flags were very much more subtle and covert.
Completely charming, almost too good to be true, and certainly was! He was a chameleon and loved everything I did, real soulmate stuff. By end of relationship he didnt agree with me on anything.
Bad relationship with his Ex, lots of drama. He used words like manipulated, controlled..I had never been used to this and it was a new language to me.
He didn't say terrible things about the Ex (he knew it was a red flag) but showed no compassion or empathy. His Ex, no overlap with me, was very bitter and therefore appeared irrational. I now think, in reflection, she had been subjected to toxic abuse and wasn't fortunate to have the resources I had (counselling and family) to heal.
Perhaps a crazy Ex , even if you witness crazy is due to the level of trauma they suffered.
Poor relationship with his mother, who had been abusive to her children. My wise mum has told me that how a man treats his mum is important but of course I knew best. The mother/child relationship especially boys is very important and if that is toxic I think there will be ongoing difficulty to form healthy relationships Ex had counselling so I assumed had done the work but narcisstic personality disorder isn't curable.
His friendships were all shallow and superficial which showed he only presented surface level stuff. He couldn't talk about someone's traits, only their status.
However biggest flag was...I felt something was off, my instinct told me to take stuff slowly but I believed I was the issue. It was my fault that I was not trusting or couldn't commit. Never, ever ignore your instincts even if you can't name them.