Starlink satellite just exploded and left 'trackable' debris

> SpaceX said it experienced an anomaly with one if its Starlink satellites that was likely caused by a small explosion. "The anomaly led to venting of the propulsion tank, a rapid decay in semi-major axis by about 4 km [2.5 miles] and the release of a small number of trackable low relatively velocity objects,"

Anyone know what relatively low velocity means… I presume it’s still pretty fast otherwise the objects would fall out of orbit immediately