Early results from a [DFG-funded study of diamond OA scholar-led journals in Germany](https://zenodo.org/record/4061304#.X5wwIC33afB): About 20 percent of the titles receive subsidies, mostly from university libraries. The authors aren't sanguine about the other 80 percent:
> All but a few key journals rely on unpaid labour and self-exploitation (e.g., by the editors, reviewers, designers). The journals do not point to a sustainable financing model.