I ran a 2-year Yoon-Suin campaign, and a good portion of the adventures were set within the Yellow City. Here are a few scenario structure
1: the big stink: No one is picking up garbage anymore, what is going on? (in Yoon-suin, the local Coackroach farmers clans do garbage disposal, but insert whatever group that would be responsible for this in your game). A new protection racket gang has moved in the city, and they are putting pressure on the waste-disposal people, who simply have left the area since they can't fight/pay.
2: Blood theft. One PC is "not from here" and their blood is a valuable component. A local slugman alchemist has a deal: why don't I take some of your blood and sell it on the market before some desperate mage puts a hit on you? PC agrees... but the blood is stolen! The alchemist is furious (he's "technically" nobility and is insulted), and it turns out that a powerful merchant has now a monopoly on the local blood trade and is behind the theft. Investigation reveals that this merchant is up to no good.... (in my game: had captive slugman as a source of blood).
3: The city is a port, and has a large granary (local farmlands are poor so it imports a lot of grain). Foes of the city attack the granary, and the PCs happen to be nearby.
4: (a hook that the PCs never followed): a local criminal gang is making fake coins. Authorities have found out and are about to crush the gang.... but a corrupt member of said authorities makes a deal with the PCs to steal most of the fake coins before the raid so they (and the PCs) can share the loot instead of it being destroyed.
In general, I would recommend Yoon-Suin as a great source for plot generation, institution/faction generation etc etc.