Is it permissible for a woman residing in Jeddah to go perform Umrah without a mahram, based on the fact that the distance between Jeddah and Makkah is not considered a distance for qasr?

The jurists have agreed that the distance for which prayer can be shortened is approximately 80 kilometers. As for a woman's travel, the authentic Sunnah indicates that it is not permissible for a woman to travel except with a mahram, regardless of the distance. Anything that is called "travel" requires the presence of a mahram.