GitHub gives you a lot for "free". In exchange they'll have no problem harvesting your data, and it would really surprise me if they aren't training on private repos too. I guess you can opt out and if they're opt out doesn't work oh well.
On the other hand Codeberg doesn't let you create private repositories at all. So Copilot could still legally scrape your open source Codeberg repos.
I don't see much of a point for most people. https://docs.codeberg.org/getting-started/faq/ >If you need private repositories for commercial projects (e.g. because you represent a company or are a developer that needs a space to host private freelance projects for your clients), we would highly recommend that you take a look at Forgejo. Forgejo is the Git hosting software that Codeberg runs. It is free software and relatively easy to self-host. Codeberg does not offer private hosting services.