I would agree that if the course faculty provide significant and non-trival starter code, then publishing the solution would be a copyright violation.

Some DMCA claims do indeed mention "The repository [from the student] contains code provided to complete assignments [georgia tech]" ([1]). But the claim at [2] does not mention this. It only says "This repository contains Georgia Tech class assignment solutions." under the section "Please provide a detailed description of the original copyrighted work".

[1] https://github.com/github/dmca/blob/master/2022/04/2022-04-0...

[2] https://github.com/github/dmca/blob/master/2022/03/2022-03-1...