The gloss is taken from the scholia to Aristophanes, Birds 158; see further below.
cf. generally kappa 1574, kappa 1575.
[1] The senses are all connected: debasing coinage can involve shaving off some of its silver content; debasing coinage is in turn the action of someone wicked (though not obviously envious) --- hence the metaphorical use of the term in Aristophanes, noted below.
[2] A distortion of the folk etymology given in the scholia to Birds: "but also [note] that coins are called adulterated (ki/bdhla), because they are manifested by [the] Chians (*xi/wn dedhlh=sqai)". (sic, i.e. the Suda gets the geography as well as the verb wrong.) The scholia and several other sources, claiming a folk etymology for ki/bdhla as xi/bdhla, allude to an incident of either Chians disfiguring Athenian coins to invalidate them, or vice versa (Tzetzes' scholia on Aristophanes, Frogs 721; scholia on Gregory of Nazianzus, Against Julian PG 36.1212d; Etymologicum Magnum s.v. ki/bdhlon). See discussion in Figueira (1998:161-163). Chios was allied with Athens, and the anecdote is hard to situate, but Figuera finds it of interest as it suggests that currency from Chios was accepted as valid in Athens (and could only be invalidated if it was already valid). Also alluded to in kappa 1575.
[3] Aristophanes, Birds 158 --- by mentioning the fact that Cloudcuckooland has no money.