Nope, it's bodies only, not stars.
By the way, the average there is around 1.5 stars per system. (The daily variations likely depend on how players are distributed over various areas of the galaxy.)
The 4-5 average likely means a smaller set of systems fully scanned, and most having only a couple of valuables scanned. Unfortunately, we don't have access to the percentages to be able to tell this.
It might be a problem for Frontier though. The Chapter Four updates have been focused on having players find the hand-crafted POIs better (shifting away from discovering the generated galaxy better), but if players are scanning less and less bodies, the chances of them finding whatever might be out there also decrease.
Of course, in the six months that have passed since, nobody has found any new Thargoid / Guardian POIs in new areas (just a few ones left out in already known areas), and no Human ones outside of the bubble's immediate vicinity. If there's nothing to be found, then players not finding them isn't exactly a problem.