[MrTerrorist]

Spoiler for Episode 16:

Kara gets exposed to Red Kryptonite(which in this universe was a failed attempt by Maxwell to create artificial Kryptonite as a weapon against Non) which brings out the worse of her which threatens National City. When the DEO attempts to stop Supergirl proves useless, Hank is forces to reveal his true form to stop Kara which later gets him arrested by the DEO.
As a result of Supergirl's rampage under Red Kryptonite, the people are afraid and lose trust with Supergirl except for a few like Cat, who despite was almost killed by Supergirl when she's was under Red Kryptonite, still trust her and gives her advice to regain the people's trust with her.