This is true for some projects, like Chromium and golang, but AFAICT not true for the majority of projects on that page. e.g. the currently most recently update

This is true for some projects, like Chromium and golang, but AFAICT not true for the majority of projects on that page. e.g. the currently most recently updated repo that doesn't have a "mirrored from..." subtitle is [1], and you can go see all the pull request activity on it (though I'm sure there are also lots of code dump repos in that list). [1] https://github.com/google/trace-viewer https://github.com/google/trace-viewer