Using a framework requires solving problems within their system and ideally their way. Especially these frontend frameworks like React, Vue, and even more so Angular from what I hear. So, being comfortable with Vanilla JS is one thing, understanding Vanilla JS well enough that you are comfortable working in different environments - because you see how it works in that framework even if it’s different - that’s another thing.
I had acquired a solid head-knowledge of JS after a year or two, but it took several years for certain practices to cement themselves that makes me more comfortable. The code I used to write I’m noticing more recently was a real mess.
And I wouldn’t say a new course is the solution, this sort of thing as maybe you’re already finding out, is best to learn on your own. See why the frameworks are the way they are by beginning building something yourself. The frameworks really just imitate how the DOM updates itself. When you start building an app or small tool you begin to see the necessity of data flow and rendering the way these frameworks do.
But you can still have preferences. I don’t like React compared to Vue. I like that I can write Vanilla JS with Vue to make components and Vue doesn’t require a web server to work (there is a script file you can include, but they support a web server model also). Vue uses attribute bindings as well where React passes data between components. I could stand to learn more.
I think my point is you’ll feel better when you begin to set your own pace and not be lead along by tutorials? Even if a tutorial or lesson had you build the thing we’re describing, being out on your own and thinking for yourself helps a lot to build that understanding.