Every part of the constellation passes over China. The Starlink satellite constellation is practically invulnerable to physical attack because it would be prohibitively expensive to hit thousands of individual satellites with interceptors. And SpaceX can keep launching them, 50 at a time (potentially hundreds at a time once Starship is working, along with an increase in constellation size to 30,000+).

Physical attacks on the ground stations are more feasible from a physics perspective, but now that the satellites have laser links you'd have to take out ground stations all over the world to completely cut service, not just locally.

The way to attack Starlink would be hacking, either of the command and control system or the user terminals. Failing that, then jamming, and/or anti-radiation missiles targeted at the user terminals. Russia is known to be trying hacking and jamming already (recall that they were already successful in hacking Viasat at the very beginning of the war). I haven't heard about them locating user terminals by their transmissions but I'd be shocked if they aren't trying that too.