What is the ruling on wearing a natural hair wig, wiping over it during ablution, and performing Umrah or Hajj with it, if the original hair has completely fallen out, and the wig is temporarily attached and known to people?

If by natural wig is meant human hair, then it is forbidden according to the majority of scholars. They cite Prophetic hadiths that prohibit hair extensions. It is forbidden to benefit from human hair due to its sanctity. This prohibition is emphasized for men. In ablution, one must wipe the head, not the wig. For someone who performs Umrah (definition) or Hajj while wearing a wig, their Hajj and Umrah are valid. However, if the person is male, he owes a fidyah (definition) (expiation) for covering his head during the state of ihram (definition).