One Piece 762 who claimed that Law was traumatized because of Vergo was Doflamingo. Also, he seemed to be trying very hard to awaken some unpleasant memories, hoping that Law could derp against Vergo because of it.
It didn't work at all.
What I'm thinking is that with all that shit happening in Law's life, it's very understandable if he got traumatized, but Doflamingo may just be misunderstanding stuff again.
Do you remember Law's reaction to Doflamingo using the Birdcage?
If anything, that looked more like a trauma to me.
Doflamingo, who has probably never loved another person in all his life imo just can't understand how you could get traumatized from bad stuff happening to others.
It's hard to make a good theory without knowing the order of events, but if all of those things happened at the end of Law's time with Doflamingo and he noticed that Law was totally out of it, he'd naturally think: "Of course, it's because he was abused by Vergo."
Then maybe he thought that this was the reason Law ran away, or something.
Uh, this is all a bit far-fetched.
What I wanted to say is that Doflamingo isn't automatically right. Like he was thinking that Law wanted to take him down to gain power at first. He didn't really seem to get that Law was coming for revenge.
That said, Vergo was only there in Law's first year with Doflamingo, after that he should have been with the marines. However, he seems to visit his boss from time to time and in the beginning, things between Law and his superiors seem to have been going well, so I don't see a reason Vergo could have had to do something "traumatizing" to him. He may have beaten him up once or twice (doesn't seem like the guy who would think much before he does that kind of thing), but I don't think that would qualify.