> Either they modified their algorithm in a way that affected values retroactively, or they're trying to disguise the fact that their previous Zestimates were w

> Either they modified their algorithm in a way that affected values retroactively, or they're trying to disguise the fact that their previous Zestimates were way off. Probably the latter. Although, it could be that the data points are calculated on the fly or starting from some arbitrary value. Then again, since it's shady to begin with, disguising their mistakes wouldn't surprise me.