Recover Published iOS App Code

An iOS app I own is live in the Apple App Store, yet the entire original project is missing—no repository access, no local backups, nothing at all. What I still hold is the production build that Apple distributes, plus my own App Store Connect credentials... (Budget: $30 - $250 USD, Jobs: iOS, iOS Development, iPhone, Mobile App Development, Objective C, Reverse Engineering, Swift, Xcode)