bp_activity_get_favorite_users_tooltip_string( $activity_id )

function bp_activity_get_favorite_users_tooltip_string( $activity_id ) {

	if ( ! bp_is_activity_like_active() ) {
		return false;
	}

	$current_user_id = get_current_user_id();
	$favorited_users = bp_activity_get_meta( $activity_id, 'bp_favorite_users', true );

	if ( ! empty( $favorited_users ) ) {
		$like_text       = bp_activity_get_favorite_users_string( $activity_id );
		$favorited_users = array_reduce( $favorited_users, function ( $carry, $user_id ) use ( $current_user_id, $like_text ) {
			if ( $user_id != $current_user_id ) {
				$user_data = get_userdata( $user_id );
				if ( strpos( $like_text, $user_data->display_name ) === false ) {
					$carry .= $user_data->display_name . '
';
				}
			}

			return $carry;
		} );
	}

	return $favorited_users;
}