Slavery had been abhorred by the general populace for quite some time, but it hadn't been completely eradicated. Many noble houses still secretly kept slaves in various places.
The church had been working to uproot the practice, but it took time for policies to take full effect. A sudden purge, where they burned everyone who owned slaves, would disrupt countless lives in unexpected ways. So, the church opted for a gradual approach, slowly making slavery less popular as the concept of free will gained traction.
In Tumidus, the port city, authorities monitored slave trading closely and heavily taxed any noble who attempted to buy or sell slaves. Eventually, slave prices became so exorbitant that raising servants from within their own households became a better option than purchasing one.