Chained unnest adds _q_0 in BQ

[z3z1ma]

To reproduce

select distinct
    @surrogate_key(u.harness_user_email, d.harness_user_id, harness_account_id) as user_account_key,
    u.harness_user_email,
    d.harness_user_id,
    harness_account_id
from
    analytics_staging.stg_mongodb__users as u,
    unnest(harness_cluster_details) as d,
    unnest(d.harness_account_ids) as harness_account_id
where harness_account_id is not null

The _q_0 should not be here?

SELECT DISTINCT                                                                                                                                                                               
  TO_HEX(                                                                                                                                                                                     
    MD5(                                                                                                                                                                                      
      CONCAT(                                                                                                                                                                                 
        COALESCE(CAST(`u`.`harness_user_email` AS STRING), '_const_'),                                                                                                                        
        '-',                                                                                                                                                                                  
        COALESCE(CAST(`d`.`harness_user_id` AS STRING), '_const_'),                                                                                                                           
        '-',                                                                                                                                                                                  
        COALESCE(CAST(`harness_account_id` AS STRING), '_const_')                                                                                                                             
      )                                                                                                                                                                                       
    )                                                                                                                                                                                         
  ) AS `user_account_key`,                                                                                                                                                                    
  `u`.`harness_user_email` AS `harness_user_email`,                                                                                                                                           
  `d`.`harness_user_id` AS `harness_user_id`,                                                                                                                                                 
  `harness_account_id` AS `harness_account_id`                                                                                                                                                
FROM (<expanded query>) AS `u`, UNNEST(`u`.`harness_cluster_details`) AS `d`, UNNEST(`_q_0`.`d`.`harness_account_ids`) AS `harness_account_id`                                                                      
WHERE                                                                                                                                                                                         
  NOT `harness_account_id` IS NULL