Is it permissible for a woman to wish she were not veiled after seeing unveiled women?

Your feeling that you are like those who do not wear the hijab, just because you see them, is an injustice to yourself. The Messenger of Allah, peace and blessings be upon him, said: "There are two types of people from the dwellers of Hell whom I have not seen: men who have whips like the tails of oxen with which they beat people, and women who are clothed yet naked, inclining [to evil] and inclined [to it], with their heads like the humps of leaning camels. They will not enter Paradise nor will they smell its fragrance, though its fragrance can be smelled from such and such a distance." And he, peace and blessings be upon him, also said: "There will be, at the end of my Ummah, men who ride on saddles similar to the large saddles, dismounting at the doors of mosques. Their women will be clothed yet naked, their heads like the humps of lean camels. Curse them, for they are cursed!" You must be proud of the hijab as an act of obedience to Allah's command and not resemble those who seek to corrupt the Ummah.