Corroded wiring casing in basement - cause?
2017 - probably MC-Lite (aluminum armor) which you could verify by magnet, but the fact that the corrosion is primarily white leans heavily that way.
Given that much corrosion in 3 years, I'd suspect that it's getting something like acidic condensate from the furnace flue (or condensate drain) dripped or splashed on it, or there's water softener salt/brine getting onto it.
A third possibility would be if there was any concrete work associated with the &quot;flipping&quot; and concrete/cement got onto the cable and was not removed - concrete and aluminum are highly incompatible.
Aside from correcting whatever is contaminating the cable, or if you can't figure out what that is, this might be a place where liquidtight conduit and THWN would be a better bet than MC-Lite.