There are passwords, certificates, API keys, more GPL code, stolen code, commercial libraries (integrated but forgot or stopped to pay the license a while ago),

There are passwords, certificates, API keys, more GPL code, stolen code, commercial libraries (integrated but forgot or stopped to pay the license a while ago), vulnerabilities, ridiculous comments, trade secrets (trading algorithms, credit score calculation, fraud detection), etc... For any sizable software that has been alive for 10 years. There is no way it's safe to open source the repo.