That's really tough. Marathon, by Bungie, is a good example of why this is tough - it's basically all the Destiny engine, network, and tooling code. When they shut down Destiny, it's not like they have a snapshot of their tooling. They've been continuously updating that tooling for ten years, and now they're using that investment for a new project.

Most game studios are similar, in reusing and improving a whole development architecture and systems across many titles. I would not agree with making them release that, even an older version. That's a big competitive moat for some studios.

I think if a community group wants to PAY to operate a server, that's quite reasonable. And then you still end up with a fight about how much to charge. But I don't think handing over server code is the right move.