That's not really how orbits work. Unless there is a stabilizing burn or very unusual conditions the debris will have an eccentric orbit, going both lower and higher than the impact point. And passing below the orbits of the starlink satellites will expose them to even more atmosphere than they will be at the starlink orbit, so their orbits will decay faster than their apogee would suggest. Sure, some will experience the right conditions to put them in an orbit such that the perigee is at the altitude of the starlink orbits or even higher, but the vast majority will not.
This does not preclude carelessness or malice causing impacts, the launch in question being the former and China's satellite destruction previously being the latter. Do you think Starlink isn't releasing their orbital paths to other launch organizations? And that net is generally very predictable. Any deviation from the existing orbit is done at the expense of the lifespan of the satellite and while there are a lot of those satellites, there's far more empty space between them. The kind of planning that rocket launches normally get is more than enough to hit those windows, along with the other windows rocket launches normally have to hit.
And one isn't even relevant in this case.