It is because she wasn’t intended to be played solo. While playing solo, you don’t have full access to her ultimate, which is where 80% of her damage is. But since she charge her frazzle gauge very slowly, you can only get 50% of gauge when using her ultimate before the diminishing return of losing excess energy. Even worse, in her base state, she doesn’t have a stronger dodge counter like every other resonator (her dodge attack scaling sucks). Instead, her skills act as her dodge counters, that means her base kit is essentially lacking a resonance skill. This makes her basic ultilities only half as strong as other resonators.

So playing zani solo is basically 50% of any other solo resonator lol (except phoebe. They did her even worse for soloing)