[throwawayffffas]

> It will be way easier to exploit potential security flaws.

It will be also easier for other people to find them and report or fix them.

In general it's a bad plan to rely on code secrecy for security. It's security through obscurity which never works out. All the cryptography schemes and algorithms are public. Most of the public internet runs on open source code. Transparency is a strength, not a weakness.