This is Rodrigo from the Zenodo team (Alex is also in CC).
Recently we have been looking into the supported metadata formats exposed via the Zenodo OAI-PMH, in hopes of discontinuing the Datacite v3 metadata prefix. From our access logs, it seems that you've been harvesting from the endpoint in this format.
Would it be possible to have a look on your side if you could easily switch over to the newest DataCite v4 (metadataPrefix=datacite)?
related to:
@slint