I worry more about their ability to detect thermal wakes.
You can detect a “wake” by satellite.
They can if they have certain equipment on the satellite.Lasers, infrared and other detectors and synthetic aperture radar (SAR). Satellites might see subtle undersea disturbances caused by submarines, watch wave patterns on or beneath the sea surface, or detect subtle variations in ocean temperature.
National Reconnaissance Office operator of the US spy satellite fleet - is planning multiple satellite launches, and China must assume that one or more of these new US surveillance satellites will help support US Navy efforts to locate and track PLAN submarines