"Now that I see you, I see there's a little bit of green in the blue of your eyes. How nice to find a flaw."
The argument can be made, IMO, that Steve's flaw was not unlike Tony's. Doing what he thought was right rather than the right thing, which isn't the same thing. No one within the MCU universe has ever acknowledged that Steve had his own agenda when the Accords first became a thing, although Rhodey touched on it a little bit when he noted that Cap's attitude was dangerously arrogant. I wouldn't call it abuse of the abilities he was given by the serum, but there is something to be said for Rogers being willing to turn his back on everything he believed in, to the point of dropping the shield like trash and leaving it behind, just for the sake of someone who was still very dangerous.
Now we have John Walker, and to an extent Karli Morgenthau. It's worth noting that Karli actually stopped for a minute after Lamar was killed, that she looked either shocked or remorseful and possibly both. Like Walker, she's also very new to the power she has, but IMO there's much more gray area where she's concerned. Killing Battlestar was terrible, but I don't think she meant to, and if it hadn't been for needing to run from a suddenly homicidal and enhanced Walker - Sam's "What did you do?!" reminded me of Monica's shock when Hayward fired that drone shot during WandaVision - she might have given up right there. If some crazy dude was coming after me with full intention of beating me to death while I'm unarmed, I'd have fucked off too.
Before the prison break, Zemo specifically told Bucky that what happened before was never personal, that he was a means to an end, which is echoed in this episode when Barnes tells Ayo that Zemo's freedom has a purpose. For good reason, Bucky doesn't like Zemo, but I don't think Zemo has any feelings about Barnes at all. If it hadn't been for who he is (was? whatever) to Steve, he'd have never homed in on him to begin with.