Not in SpaceX’s case. The satellites are in low enough orbit to deorbit themselves naturally if they fail, although they do so faster if using onboard thrusters at end of life. Any debris caused by failure is also likely to deorbit quickly. Not true for higher orbits, like 800km or above.

As far as being visible to sensitive telescopes, that is true, but also not surprising. Telescopes are designed to detect really faint things, so even though Starlink is now almost always darker than the visible limit once fully deployed in operational orbit, it can still show up in sensitive astronomical surveys.