bp_rest_sanitize_member_types( string $value )

function bp_rest_sanitize_member_types( $value ) {
	if ( empty( $value ) ) {
		return $value;
	}

	$types              = explode( ',', $value );
	$registered_types   = bp_get_member_types();
	$registered_types[] = 'any';
	$valid_types        = array_intersect( $types, $registered_types );

	return ( ! empty( $valid_types ) ) ? $valid_types : null;
}