>SpaceX deploys its satellites into these lower obits so that in the very rare case any satellite does not pass initial system checkouts it will quickly be deorbited by atmospheric drag. While the low deployment altitude requires more capable satellites at a considerable cost to us, it’s the right thing to do to maintain a sustainable space environment.
https://www.youtube.com/watch?v=5ijKirDjwOU
The Gabbard diagram is a way of expressing the orbital locations and decay of the particles produced as a result of an orbital collision. Note how higher objects tend to stay high for a long time, but low objects (below about 600km) drift lower at an appreciable timescale, and once they're below about 500km they fall the rest of the way very very quickly.
Starlink satellites deploy to 550-km orbits.
Edit: Oh, these were launched into a 210-km orbit, which combined with the higher atmospheric density due to the geomagnetic storm, basically dragged them back down before they could raise to their normal orbit. Oof.
Also, the vast majority of SpaceX satellites will be at 350km.
They start off at a 350 km ( https://in-the-sky.org/spacecraft.php?id=50803 was launched earlier this year).
They then raise them to about a 550 km orbit for its operational lifetime ( https://in-the-sky.org/spacecraft.php?id=45102 )
And then they lower it a bit, and it decays more rapidly ( https://in-the-sky.org/spacecraft.php?id=44249 )
Another one that didn't go operational - https://in-the-sky.org/spacecraft.php?id=44282 - you can see it go up, fail, get lowered, and decay.
https://en.wikipedia.org/wiki/Starlink#cite_note-sn20170917-...
I am not aware of any Starlink satellites currently in either of those two orbits.