You Do Need power plug adapter while traveling from Nauru to Mayotte.

Here is Why You Need An Adapter

The outlet and plug type used in Mayotte are C and E and in Nauru is I. This is how they look like.

Nauru

In Nauru, outlets of type I are in use.

Type I

Mayotte

In Mayotte, outlets of type C and E are in use.

Type C

Type E