I'm also leaning into the camp that the Man in the Iron Mask is the real Jay Garrick of Earth-2, and that the Jay Garrick we've come to know and love is really Hunter Zolomon of Earth-2. I also think the notion that, if that theory is true, then the real Jay and Earth-2 Hunter are identical twins. Perhaps, when Jay on Earth-2 became the Flash, Hunter became jealous of his brother for getting powers while he didn't. So Zoom approached Hunter and told him "I can give you all the speed you want if you help me take out your brother." So Hunter did, took his brother's place by pretending to be the Flash, and Zoom gave Hunter Velocity-6 to mimic Jay's speed. But of course, since Velocity-6 is only a temporary boost and highly addictive, Hunter had to keep coming back to Zoom for more, but only if Hunter did what Zoom told him to do. Like go to Earth-1 and infiltrate Team Flash as Zoom's spy and gain their trust. But of course, Hunter has come to genuinely like Team Flash, especially Caitlin, but he can't tell them he's not the real Jay Garrick or that he's working for Zoom.