Ask HN: Greybeard cowboy coder looking for advice on being more professional

I've been a self-taught web developer for 16 years and am currently in the job market. I've been getting some take home coding assessments that don't look like anything I've encountered in my career so far. I've always assumed that there were holes in my knowledge due to the way I taught myself, which was essentially develop the logic in my head and then look online on how to manifest that logic in the language the project uses. It's gotten me pretty far, but I believe I've hit the limit and feel that I'm stuck as a intermediate developer. I think it's time to take a few steps back and "relearn" web development.

I've just purchased several udemy courses on computer science and various languages. Can anyone suggest any other ways to fill the gaps in my knowledge? Specifically, I'm looking for:

Books

Blogs

Podcasts

Online Courses

Any other tips

Thanks!

EDIT: The "Professional" descriptor in the title isn't referring to corporate office professionalism. I'm more referring to professional proficiency.