src/Jobs/Collection.php
public function failed(): array
    {
        $results = json_decode($this->client->failed(), true);

        return is_array($results) ? $results : [];
    }
public function failed(): array
    {
        $results = json_decode($this->client->failed(), true);

        return is_array($results) ? $results : [];
    }
Fetches a report of failed jobs, where the key is the group and the value is the number of jobs

@return array