In a new article, Phys takes a look at the failure rate of these satellites and the possible concerns associated with this. Estimates point to a current failure rate of 3 percent for the Starlink constellation, which is not that bad. However, one of the concerns is that such a huge constellation will result in a lot of bad space junk:
But every satellite that is incapable of maneuvering due to problems with its communications or its propulsion system creates a collision hazard for other satellites and spacecraft. As McDowell told Business Insider:The article has more info about concerns and possible mitigation.
"I would say their failure rate is not egregious. It's not worse than anybody else's failure rates. The concern is that even a normal failure rate in such a huge constellation is going to end up with a lot of bad space junk."