What is the ruling on naming girls Mufazah (مفازة) or Mufazan (مفازاً)?

There is no objection to naming a girl Mafazah, because its linguistic root is from "al-fawz" (success/victory), and its meaning is "al-manjah" (salvation/deliverance). It may also be applied to a vast land as an optimistic sign of safety, success, and deliverance for anyone who passes through it. The basic principle regarding names is permissibility.