Which isn't hard to do if you have the budget of a government. Directional antennae, GPS and a helicopter/Cessna flying patterns over a metro. Beams from the terminal are constantly scanning the sky chasing the constellations.
A higher hit rate option would be a fleet of low altitude drones taking high-res pictures of the ground, and running a fine-tuned classifier to identify Starlink Dishies which require a clear line of sight to the sky.
People who think Starlink is unblockable, or somehow anonymous IRL are unimaginative. Iran is well-versed enough with electronic warfare that it tricked a RQ-170 Sentinel land on it's territory - how hardened are Starlink terminals against responding to a spoofed signal and exposing their locations?