Here, (Ag2S) twice as many ions of Ag are produced compared to S ions meaning Ag2S will be even less soluble in a solution composed of AgNO3 (as Ag ions are already present and due to the 2:1 addition of Ag) than K2S which has S ions (Ag2S only adding a 1 mole equivalent of S ions). Trying to just explain this simply idk if that helps. If not I could try to re-evaluate or someone else might be able to add to this.