However, earlier, during the USJ attack, she was kinda bummed out and she thought "why aren't we really doing anything to the villains?"
She was laying low, because again, she didn't really want to deal with heroic stuff. She was kinda lazy too.
But when All Might arrived and Shigaraki was fighting back, she kinda started focusing more because she adored all might like a dad (since he kinda raised her for a few years).
And that moment that Shigaraki decided to retreat, she yelled at Momo to craft a pair of handcuffs and without thinking teleported behind Shigaraki to restrain him before he could flea. She managed to grab onto him and throw her arms around his torso, clinging to him to slow him down and hopefully get the cuffs on his wrists. But at that moment, Snipe had already fired bullets his way... So Jiki ended up ensuring most of the brunt, while Shigaraki only had a few bullets hit him.
When they both got hit with the bullets and Shigaraki kind of yelped a little, it was like something snapped in her mind and heart and she was like, "wait... Should I really be fighting him? Shouldn't heroes save people, even if they're bad?"