Job xxxxxxxx not cancelable

I notice in my cockroach cluster some jobs which seems to run endless.

root@cockroachdb-public:26257/defaultdb> show jobs;
        job_id       |     job_type     |              description               | statement | user_name |  status   |   running_status   |             created              |             started              |             finished             |             modified             | fraction_completed | error | coordinator_id
---------------------+------------------+----------------------------------------+-----------+-----------+-----------+--------------------+----------------------------------+----------------------------------+----------------------------------+----------------------------------+--------------------+-------+-----------------
  653912175832727553 | SCHEMA CHANGE GC | GC for DROP DATABASE defaultdb CASCADE |           | root      | running   | waiting for GC TTL | 2021-04-28 16:49:19.128613+00:00 | 2021-04-28 16:49:19.155431+00:00 | NULL                             | 2021-04-28 16:49:19.193027+00:00 |                  0 |       |           NULL
  653912175454093313 | SCHEMA CHANGE GC | GC for                                 |           | root      | running   | waiting for GC TTL | 2021-04-28 16:49:19.013075+00:00 | 2021-04-28 16:49:19.032704+00:00 | NULL                             | 2021-04-28 16:49:19.053517+00:00 |                  0 |       |           NULL
  653961632001163267 | SCHEMA CHANGE    | updating privileges for table 59       |           | root      | succeeded | NULL               | 2021-04-28 21:00:51.923228+00:00 | 2021-04-28 21:00:52.005148+00:00 | 2021-04-28 21:00:58.068015+00:00 | 2021-04-28 21:00:58.0649+00:00   |                  1 |       |           NULL
  653961632039141379 | SCHEMA CHANGE    | updating privileges for table 62       |           | root      | succeeded | NULL               | 2021-04-28 21:00:51.923228+00:00 | 2021-04-28 21:00:52.005147+00:00 | 2021-04-28 21:00:52.106378+00:00 | 2021-04-28 21:00:52.105258+00:00 |                  1 |       |           NULL

If I try to cancel such a job I got an error message:

root@cockroachdb-public:26257/defaultdb> cancel job 653912175454093313;
ERROR: job 653912175454093313: not cancelable

Is this something I should be concerned about?

Thanks for any help.

Those jobs are totally normal! When you drop a table or a database we create asynchronous jobs to later clean up the data. That job should clean up the data after the GC TTL expires for that data.