Unauthorised Github Repository Access

On 29 May 2025, a developer from People Per Hour created an unauthorised GitHub repository containing my website's code. I cannot disconnect developer mode, as I may lose all changes to my website. I do not have access to the GitHub account to check the repository's settings and change the access. Is there a technical workaround to locate and access the GitHub repository? I have tried contacting the only two developers to whom I granted website admin access for access to the GitHub repository, but I have yet to receive a reply. There are no issues with the website; the problem is access to the Github repository.