xprofile_filter_get_user_display_name( string $full_name, int $user_id )

function xprofile_filter_get_user_display_name( $full_name, $user_id ) {

	if ( empty( $user_id ) ) {
		return $full_name;
	}

	if ( !empty( $user_id ) ) {

		$display_name = bp_xprofile_get_member_display_name( $user_id );

		if ( !empty( $display_name ) ) {
			$full_name = $display_name;
		}

		$list_fields = bp_xprofile_get_hidden_fields_for_user( $user_id );

		if ( ! empty( $list_fields ) ) {
			$last_name_field_id = bp_xprofile_lastname_field_id();

			if ( in_array( $last_name_field_id, $list_fields ) ) {
				$last_name    = xprofile_get_field_data( $last_name_field_id, $user_id );
				$full_name = str_replace( ' ' . $last_name, '', $full_name );
			}
		}
	}

	return $full_name;
}