The Shu”t Beis Yehudah (siman 43) writes that it’s obvious that there is no difference between kiddush and havdolah. Certainly, according to the Rambam that havdolah is de’O’raisa it’s the same, but even if havdolah is derabonon, it was enacted in a similar way to the de’O’raisa, therefore, the same halachos apply.
The Shu”t Divrei Malkiel (4:1) discusses at length about using uncovered wine for kiddush, and at the end of the Teshuvah he writes, this is all in regard to kiddush on Friday night, however, for kiddush on Shabbos day, and for havdolah it’s ok, as one can even use other beverages on those occasions.
Regarding that which the Divrei Malkiel writes, that for kiddush on Shabbos day it’s ok, it’s clear from the Chayei Adam quoted by the Mishnah Berurah that he disagrees. The Chayei Adam writes that when using beer, one should be more stringent. Beer can only be used in the day, therefore, it’s clear that the Chayei Adam learns that uncovered wine is a problem in the day as well. See the Sha’ar HaTziyun who already points this out.
The Orchos Chaim (Hilchos Shabbos 64, ois 22) writes that one shouldn’t make havdolah using uncovered wine. R’ Chaim Palagi (Orach Chaim, siman 13) asks, that the din of uncovered wine is only mentioned by kiddush? He then brings a
