The Dragon capsule has been relatively quiet on S-Band after docking. Last mission, S-Band remained active while docked, this has not been the case this mission.
However, Dragon has been transmitting on UHF (400.5 MHz) sending telemetry using it’s COTS UHF Communication Unit (CUCU) continuously. This seems to be a very low power transmitter, likely using an omni-directional antenna, perhaps just for Dragon/ISS command/control.
Below is a screenshot of this signal.