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

Here is Why You Need An Adapter

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

Gambia

In Gambia, outlets of type G are in use.

Type G

Mayotte

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

Type C

Type E