Starlink's birds are, according to publicly available information, to be put in a quicky decaying orbit.

In the event of a nuclear war, as suggested by an ancestor post, someone will almost certainly attempt to use anti-satellite missiles as part of their first-strike protocol--especially against those satellites suspected of providing early warning for ICBM launches. Same deal for radar tracking sites. Blind the enemy. The enemy launches everything they have because they're blind, and think your missiles are already incoming.

Maybe someone launches anti-ballistic-missile missiles, and scores a few hits. Debris is spreading to all kinds of orbits. Kessler Syndrome will be the least of our problems as the bombs fall, but it'll be a pain later, after the fallout clears.