[Someone]

> Is C maintained like other languages

Yes. Like, for example, JavaScript, Scheme, Fortran and Common Lisp, it is a specification for a programming language that is maintained by a committee/working group

> with public repo, releases and issues?

No. Not being a language implementation, there are no releases other than the standards.

Issues and prereleases typically are discussed by the committee, with some results and progress (including some drafts of new versions) getting published before release. see thttps://www.open-std.org/jtc1/sc22/wg14/