Ah I see, sorry. When you wrote "Configure DataCite harvesters to use the oai_datacite export format," I assumed that meant that you were using Dataverse's OAI-PMH harvesting feature so that other repositories or systems could harvest metadata from the repository that you manage.
But since you've written that you "expected to find data on funders on Datacite, but instead, it's not being collected", this makes me think that your goal is to make sure that DataCite has your repository's funding metadata. In that case, that "DataCite" export format you mentioned shows what metadata is being sent to DataCite when datasets in your Dataverse repository are created and updated.
And what Jim wrote about upgrading to v6.4 sounds to me like the best way to do this, too. The upgrade instructions should include steps for sending the additional metadata to DataCite.
I hope that clears things up!
About that "oai_datacite" export format you mentioned, its design was informed by OpenAIRE's metadata guidelines for data repositories and was created so that folks can set up harvesting between their repositories and OpenAIRE's systems. OpenAIRE's metadata guidelines are informed by DataCite's metadata standard, which I think is why folks at OpenAIRE expect the metadata format to be called "oai_datacite", and why the folks who designed Dataverse's "oai_datacite" export format named it "oai_datacite". I think they also did this before others added Dataverse's "DataCite" export format in order to show what metadata is sent to DataCite. I think of this situation kind of like how we called Earth's moon "moon" before we discovered that other planets have moons, too. I wrote about this (the naming confusion and related challenges, not the moon thing
😂) in the GitHub issue at
https://github.com/IQSS/dataverse/issues/5889.