I have so many theories, but I'm guessing:
1. Someone in the govt made this group to be a fake adversary for John Walker
2. John Walker is supposed to take this group down, get his shining moment and be the Cap the government wants, one they can control because they couldn't control Steve
3. The group goes through their SSS treatment, this causes them to become insane and they also meet Zemo and become radicals
4. Walker eventually finds all this out, but he is also going insane from a serum he received
5. Walker is ashamed and that's why we see him on his knees in that one screenshot
6. It is up to Sam and Bucky to stop these radicals
If I can guess, the US Govt. still has the SSS they gave to Emil Blonksy which made him go insane. I'm guess Walker and the Flag smashers probably all have variants of this serum.
Attachment 107070
I know this scene and it looks like these are linked together
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