Business source license. Free for personal or commercial use. But service providers have to pay if they offer this database as a service.
The LICENSE file even contains the following part:
> The Business Source License (this document, or the “License”) is not an Open Source license. However, the Licensed Work will eventually be made available under an Open Source License, as stated in this License.
And README mentions nothing about FOSS/OSS, so seems the submitter here on HN added it themselves to the title. Should be removed.