While most people correctly state that Jinx ruined Zaun's chance at independence in s1, it would be even more correct to argue that Jayce (and Vi) ruined it first. Mel and the Council were willing to hear Silco's demands, when they learned about him. Would have gotten a completely independent Zaun? Probably not. But Silco didn't think he'd get literally everything he wanted, he was willing to negotiate (haggle).
It was Jayce who went around the Council's (and Mel's) back to raid the refinery (without a warrant) because he didn't like the idea of talking things out, he wanted retribution. All he ended up doing was getting a lot of people killed and assaulted, including a child. And once Jayce learns his lesson, without telling anyone (again), he offers Silco Zaun's independence, which was an offer doomed to fail because not only was their talk not a negotation but a series of demands made by Jayce. He also pushed what were essentially two non-starters.
Jayce demanded Jinx's arrest, which is an insane thing to demand from someone that would technically be a leader of a sovereign city-state, if Silco went through with the deal. Jayce was asking Silco to hand over his daughter to a foreign government and be imprisoned by them. Let's look outside Jinx's crimes for a second. How does that not sound like Piltover wants to hold hostage the child of their political rival as a bargaining chip.
Second, and is so because it's less discussed, Jayce wanted to end all shimmer manufacturing. What does that mean for Silco when he literally uses it as medicine for his infection? It means he'll die without it.
People can say Jinx ruined PnZ's chance for peace, which is true, but only in that she sped up the inevitable breakdown. Silco was never going to give Jinx up (it's weird to think he'd give up shimmer too). A war between Piltover and Zaun was inevitable because Jayce had to put his foot in it so many times.