It would have actually been interesting if Bra pulled a Toguro and embraced her actions, even saying something to the effect of wanting to be a "true" Saiyan, bloodthirsty and obsessed with power at all costs and living according to her own ideals and values of what she thinks makes might & right. Like what Vegeta wanted to be, expect he didn't actually believe his own BS. It'd be much more interesting if Bra instead used the Majin mark as an opportunity rather than throwing an even less likable version of Vegeta's tantrum.
U18 Bra would have nothing on her in any regard. In that case, I could 100% see Bra logically punching U18 Bra in half or something equally gratuitously gory. Because why would she doubt herself? She actually believes in something and is following some sort of fascistic value system, so "you're a violent creep who is so weak and scared of being seen as weak you let yourself be mind-controlled" could be followed up with "Yes, because I chose to be."
Instead, what we got was:

If for attention, insert Linkin Park's "Crawling"
If for results, insert Papa Roach's "Last Resort"
Just.... yikes.
I don't believe the consequences. Dragon Ball already has no consequences; it's mostly flashy fight scenes at this point. Boo killed billions and him simply deciding to not kill anymore was enough to get people to think he was redeemed; Vegeta was even worse because he knew better and he's now a lovable family man with an apocalyptic death toll behind him. This tournament is so bunk you could sleep on it— everyone's going to be revived at the end anyway, so why bother getting mad at a death? Even a slaughter?
The attempt to make Bra sympathetic is unbelievable. But worse than that... it's just pathetic! I'm not against remorseful characters, even those who have done Holocaust-tier evil (remorse in the face of unforgiveness is a good story type anyway), but goddamn so many opportunities were missed that it's achieved quantum superposition. It would have been so much more interesting if Bra didn't start freaking out in that implosion of teen angst and instead fully embraced the dark side on her own volition. I'd actually have considered the arc worth it and even come dangerously close to considering Bra decent if she just took some fuckin' agency. Hell, Salagir seemed to be leading up to that with the flashbacks and whatnot. All of that could've been salvaged if Bra just said, "I choose to do what I do."