I noticed long ago that unreferenced commits survive on GitHub for long, but I couldn't find a way to discover them.
I know that GitHub stores together the objects of many repositories, but they should have implemented and offered a way to gc them when they came up with that optimization.
Sure, there would still be the chance that someone already obtained the objects by the time you gc them, but it's a much lesser risk then leaving them there indefinitely (and they could provide a log of the last fetches to better assess the impact of the erroneous push).
I was under the impression that there are various 'mirror github' projects that listen to the GitHub change event API and immediately crawl some/all commits.
If so, this isn't a chance - it is certain.
The blog post was most likely this one: https://github.blog/2022-09-13-scaling-gits-garbage-collecti...
And I think it answers the product vision for it well (why it’s automatic):
> We have used this idea at GitHub with great success, and now treat garbage collection as a hands-off process from start to finish.
GitHub also provides these docs for what to do if there is sensitive data in your repo, which is quite involved and (given the huge amount of knowledge internally of both GitHub internals and git internals), I would trust their advice:
https://docs.github.com/en/authentication/keeping-your-accou...
You can also contact support or create/join a community discussion: https://github.com/orgs/community/discussions
If you feel strongly that a feature you need is missing, by adding your voice, you increase visibility of the request. I think GitHub does offer solutions to this problem though, including eventual GC automatically.
To a certain extent, your approach of considering any mistakenly pushed commit as public is laudable, but it still seems unreasonable to me to not provide an analogue to gc