I have not been able to find information online to chart out the SpaceX Starlink launches to see which have announced instantaneous launch windows and others are not announced as such, leading to my assumption that some Starlink launches do not have an instantaneous launch window. Which leads to my question - if Starlink satellites have their own thrusters to maneuver into proper orbits once deployed, why would there be a need for an instantaneous launch for them?
I could see a need for specific orbital-position launches to be instantaneous (such as a manned launch to rendezvous with the Space Station where time/position in orbit needs to be very precise right off the launch), but for Starlink, there doesn't appear to be that time criticality, and they seem (at least to the novice observer) to be quite independently maneuverable and time to final position isn't nearly as important.
But maybe all Starlink launches are instantaneous, and just aren't all announced as such.