It means there will be a proprietary version of Gitea, named Gitea Enterprise or something similar. The company is based on an Open Core business model https://en.wikipedia.org/wiki/Open-core_model.
Is it? The blog post calls out their participation with Blender, and reading the linked blender posts and videos where they talk about their work with the company they talk about the relationship being entirely about providing advice and support, I don't think blender bought some closed source software.