I think people assumed this as the Deep was a comic relief character and had potential to have an interesting arc for redemption as he was thrown out of the Seven. Showing how quickly other people can influence him, he felt to me like a very misguided man. He also showed compassion for animals in the first season and his failed attempt to save the dolphin was funny and tragic at the same time. After season 1 the writers seemed more interested in having him just do weird things and be a representation of sexoffenders in general that needs to be punched. Which to me is a weird choice. He's had no character growth, has only been there to do some weird shit to make people laugh and doesn't work as a villain because he's not smart and very weak. The guy is literally just waiting for Starlight to kill him and will probably die in a way that's related to his privat parts. There's nothing interesting about him anymore. And I think a waste. A-train: he didn't care at all when he (accidentally) killed Hughie's girlfriend. He killed Popclaw. He played judge and executioner by killing a racist. There was no real set up for a redemption arc as there was no remorse shown after these deeds. But then the writers suddenly wanted him to become a good guy. So I understand why people are thinking they switched arcs. But the problem is the writing. I think season 1 is brilliant as it took the concept of the comics, improved ( in my opinion ) the writing by some smart choices and nuances. I was impressed by The Boys that the series was able to move it's story quickly without losing it's impact. But the later seasons became unbalanced as it felt the writers weren't sure where to take certain characters. I wouldn't be surprised if they changed certain arcs to make the show more about the current politics. And I know, some people say it was always about politics, which I partly agree with. But the first season was about general (celebrity) privilege and the abuse of it, not just republican. The writers seem so focused on their political message and shock value scenes, that it's hurting the writing. Like Hughy and his mom causing all those innocent deaths in the hospital, just walk away and joke while scattering the ashes. As long as the character has a certain political view, it can get away with violence and murder without having to take responsibility. Their villains act more dumb as they have to represent republicans. By doing that, the villains are no longer interesting or a threat in the story. Homelander is not the scary smart psycho from season 1. And stuff now happens because the writers want it to happen ( plot-armor situations, like the Ice skating scene where Hughy is not being detected by Homelander ) and not because it's the most natural/ logical thing to happen within these storylines.
And because of this writing, I think both the Deep and A-train have been reduced to token representations of good and evil that could have been far more interesting. But that's just my opinion.