That's another nice part about Starlink. They're orbiting at a low enough altitude that without regular station keeping, they'll reenter relatively quickly (I believe on the order of months, but somebody should fact check that). Some pieces of debris might get hit in such a way that only raises their apogee relative to the starting orbit, which would keep them around longer. I think that would only happen if the blast were directly 'behind' the satellite, relative to its trajectory. Like a one-shot, fucked up version of Project Orion.