They do talk about that a bit in the article: "These candidates await spectroscopic confirmation: Their redshifts are only estimates for now. But so far, spect

They do talk about that a bit in the article: "These candidates await spectroscopic confirmation: Their redshifts are only estimates for now. But so far, spectroscopic confirmations of other galaxies have confirmed the vast majority of preliminary distances. Even if only half of Yan’s selection turn out to be nearby galaxies masquerading as distant ones, the latter number would still be unexpectedly large."