As far as I'm aware this is now the largest public repo to get synced between GitHub and another platform at ~18k PRs, ~4k issues, and over 200k total items between checks, comments, prs, reviews, etc
There are other git projects hosted on multiple platforms. Pretty sure linux kernel is hosted in more places than github, and kept in sync because it's based on git.
What research did you base this on?
Then why are you bringing it up like it's something impressive???