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

Here is Why You Need An Adapter

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

Brazil

In Brazil, outlets of type C and N are in use.

Type C

Type N

Mayotte

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

Type C

Type E