Concept/Parent id API requests give 404 error

[wragge]

Describe the bug

When I attempt to access records using their concept ids via the API I get a 404 error. So for the concept id 6339873:

• https://zenodo.org/records/6339873 <-- works as expected, resolves to latest version
• https://zenodo.org/api/records/6339873 <-- gives a 404 error

I can access the record for the latest version via the API as expected: https://zenodo.org/api/records/6339883 This record includes the failing concept url at record["links"]["parent"]: https://zenodo.org/api/records/6339873

I have tried this with a number of concept ids and get the same result. I have previously been able to access the concept urls without error, so I assume something has changed with the recent update?