The universe is our trash can

LEO satellites, like the ones being discussed, are pretty much guaranteed to deorbit within a limited timeframe, as atmospheric drag constantly causes their orbit to decay.

That doesn’t mean that you couldn’t colossally mess up the existing LEO satellites, but that mess would clean itself up within a few years. And you have to put new LEO satellites up every few years anyway, so it’d translate to a relatively-short-term – if significant – disruption.

The real problems are higher-altitude satellites.

https://en.wikipedia.org/wiki/2007_Chinese_anti-satellite_missile_test

More than half of the tracked debris orbits the Earth with a mean altitude above 850 kilometres (530 mi), so they would likely remain in orbit for decades or centuries.