Low earth orbit is anything below 2000 km. Starlink, the largest constellation by far, operates at or below 570 km. A new batch launched to 340 km was hit by a geomagnetic storm a few months ago, passively coming down within a few weeks. They can also use their ion propulsion systems to come down faster.

Space News article;

"FCC to set five-year deadline for deorbiting LEO satellites'

https://spacenews.com/fcc-to-set-fiv...eo-satellites/

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For the 2022 International Astronautical Congress (IAC 2022), space companies Iridium, OneWeb, and SpaceX (Starlink) have presented a joint paper;

"Satellite Orbital Safety Best Practices"

PDF...
https://www.ascend.events/wp-content...neWeb-AIAA.pdf