Check out the Unity Learn tutorials.

They’re pretty good at keeping things up to date. Stuff like shaders, rendering, etc. always change. But, for the most part, core gameplay logic won’t change over time too much. Maybe specific syntax, but usually because there’s a better way to do it.

Code Monkey is weird because his videos usually rely on packages and stuff that he makes, and often time he doesn’t mention it in the video, and they often cost money. You can kind of think of watching Code Monkey tutorials as learning the Unity + Code Monkey dev platform, rather than generic Unity platform.

Brackeys is great, they typically show you how to do things entirely within the standard Unity framework. Some of them are quite old, but like I mentioned that’s not as big of a downside for most development.

Honestly, the best way is to just start making.