> You may convey verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice; keep intact all notices stating that this License and any non-permissive terms added in accord with section 7 apply to the code; keep intact all notices of the absence of any warranty; and give all recipients a copy of this License along with the Program.
https://www.gnu.org/licenses/gpl-3.0.en.html
If GitHub uses the source code in a way that violates the license, there is no provision in the GitHub terms of service that would allow GitHub to deflect legal liability to the GitHub user who uploaded the program. The uploader satisifed the requirements of GPLv3, and GitHub would be the only party in violation.
If you can't actually grant that separate license, you're misrepresenting your ownership and license to that code
> If you upload Content that already comes with a license granting GitHub the permissions we need to run our Service, no additional license is required.
https://docs.github.com/en/site-policy/github-terms/github-t...
and section D4 does not mention any permissions that GPLv3 does not already cover. GitHub automatically recognizes when a repo is GPLv3-licensed, so it cannot claim ignorance of what GPLv3 is.
If you're posting anything you did not create yourself or do not own the rights to, you agree that you are responsible for any Content you post; that you will only submit Content that you have the right to post; and that you will fully comply with any third party licenses relating to Content you post.
I suppose this means if I upload your stuff to GitHub, and you sue GitHub, then GitHub would be able to somehow deflect liability onto me.