Ask HN: How can I learn how to write professional production level code?

I am a young indie hacker, I know how to hack around a fullstack app, I have built not so complex saas apps, which have earned me some money. But I still feel like I am below those who have worked at some place . Some of these terms people use and other stuff has made me doubt myself at many times and is starting to affect my confidence. Is there a way for me to learn all the stuff they teach at companies by working in Open Source projects? I don't want to take a job, I don't want to spend time on interview and all. All I need is knowledge and mentorship . Will Open Source be enough?