Seeing as how the "flea ship" first showed up on VOY in the Delta quadrant (even if that version was much smaller and it was a couple of hundred years later in trek time), could it have been something recovered by the romulans, complete with cloak and holo-tech they didn't have, and maybe even a quantum singularity power plant?
Or maybe a Romulan Drone ship found its way to the DQ shortly after the Coalition/Star Empire War and was found adrift by the unknown flea ship aliens and used for 200 years as a transport ship until it strayed into Chaotic Space?
