Is it Islamically permissible to wear an inflated or elevated hijab, known as "bu nafkhah" hijab?

If the hair tie is on top of the head, then it falls under the warning that its doer will be threatened with Hellfire, based on the Prophet's (peace and blessings be upon him) saying: "There will be women who are dressed yet naked, inclining [to evil] and inclining [others] to evil. Their heads are like the humps of leaning camels." However, if it is not on the head, then there is no harm in it, unless it has a noticeable mark appearing from behind the abaya, in which case it would be a prohibited display of adornment (tabarruj). As for the lawful hijab, it has conditions that have been previously explained, and any violation of them makes the hijab forbidden.