I have the impression that in the april 2025 release zwift added some sort of algorithm that somehow changes the power target in erg mode before sending it to the smart trainer. Before it worked perfectly fine, but since then some weird anomalies happen. Like indeed sometimes it feels as if the gradient affects the power, often increasing cadence also increases resistance (which should not be the case in erg mode), … I’ve made a post about it a while ago Bad experience with ERG mode since April - #11 by Glenn_Van_Loon .