https://gitlab.com/gitlab-org/gitlab/-/merge_requests/50824 renamed the application setting from `asset_proxy_whitelist` to `asset_proxy_allowlist` and also removed the serialization code from the old column. This caused https://gitlab.com/gitlab-com/gl-infra/production/-/issues/3494 because before the migration (renaming the column) the Rails code was trying to use load the new (but not yet existing) and fell back to the old (existing but unserialized) column which returned a YAML string instead of any Array. See https://gitlab.com/gitlab-org/gitlab/-/blob/9f4230b0e639dd2659ddb2edc0aaf37c043d2c84/lib/banzai/filter/asset_proxy_filter.rb#L62-63 To mitigate this failure https://gitlab.com/gitlab-org/gitlab/-/merge_requests/53272 brought back the serialization code for the old column which should be removed in the next release.