Steps to retest:

1. Create a CCV and add a CV that contains a docker repo.
2. Publish the CCV which will create version 1.
3. Run the following commands to get all orphaned Katello::DockerMetaTag records.

foreman-rake console
Katello::DockerMetaTag.where("id not in (?)", Katello::RepositoryDockerMetaTag.pluck(:docker_meta_tag_id)).size
exit

4. Verify that the record returns 0
5. Remove the CCV version 1 and wait until the task is finished.
6. Repeat step 3
7. Verify that the record returns 0

Expected:
4 & 7)
# foreman-rake console
Loading production environment (Rails 6.0.3.1)
irb(main):001:0> Katello::DockerMetaTag.where("id not in (?)", Katello::RepositoryDockerMetaTag.pluck(:docker_meta_tag_id)).size
=> 0
irb(main):002:0> exit

# foreman-rake console
Loading production environment (Rails 6.0.3.1)
irb(main):001:0> Katello::DockerMetaTag.where("id not in (?)", Katello::RepositoryDockerMetaTag.pluck(:docker_meta_tag_id)).size
=> 0
irb(main):002:0> 


Actual:
4 & 7)
# foreman-rake console
Loading production environment (Rails 6.0.3.1)
irb(main):001:0> Katello::DockerMetaTag.where("id not in (?)", Katello::RepositoryDockerMetaTag.pluck(:docker_meta_tag_id)).size
=> 0

# foreman-rake console
Loading production environment (Rails 6.0.3.1)
irb(main):001:0> Katello::DockerMetaTag.where("id not in (?)", Katello::RepositoryDockerMetaTag.pluck(:docker_meta_tag_id)).size
=> 0

Verified on 6.8.2_01

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Satellite 6.8.2 Async Bug Fix Update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:5467