The Starlink constellation is launched into an insertion orbit at 200km where the decay time to reentry is measured in days, before being raised to 500km where the life, if not maintained by using fuel, is about a decade.
The OneWeb constellation, for which Arianespace has just launched the latest batch, as launched into a 500km insertion orbit with a decay time of about a 10 years, before being raised to a 1200km orbit with a decay time of millennia.
Which is causing the greater long term problem?
Which, by the way, is why the FCC gave SpaceX permission for 2,800 more satellites - because they lowered their planned orbits from 1200km to the same 500km orbit as the present constellation.
https://spacenews.com/fcc-approves-s...-modification/