Currently the toolbox image sets no value - either toolbox.image needs to be unset to default to the ceph value or the value should not be commented. I've commented the whole line here as the template shows this is the desired behaviour:

      image: {{ default .Values.cephClusterSpec.cephVersion.image .Values.toolbox.image }}

Issue resolved by this Pull Request:
Resolves #14180

Checklist:

• [ x] Commit Message Formatting: Commit titles and messages follow guidelines in the developer guide.
• [x ] Reviewed the developer guide on Submitting a Pull Request
• [ x] Pending release notes updated with breaking and/or notable changes for the next minor release.
• [x ] Documentation has been updated, if necessary.
• [ x] Unit tests have been added, if necessary.
• [ x] Integration tests have been added, if necessary.