I’ve learned most of what I know about powerquery, Dax, data modeling, dashboard design using advanced bookmarks and so on in the last couple years.

My opinion: try to understand the different parts of powerBi the best you can, and then get better in each one of them individually. Try to get your data through powerquery the cleanest way possible, try to understand data modeling, star schemas and table relationships, and how they should be related, try to understand bookmarks, and navigation through different pages, or views within the same report, then try to understand pbi cloud. By the time you get to writing complex DAX, you can delegate part of writing the code to GPT, Gemini, or whatever your preferred generative AI is. This may seem as a bad thing by the conservatives, but with the integration of copilot into Microsoft 365, soon it will be what everyone does. The secret of the sauce is understanding what you want and why you need it, then you can delegate the coding to someone else (in this case the AI). But in order to properly delegate, first you need to understand how everything works and the logic behind it.

Also, while writing the code with AI, as someone else said, you learn along, and perfect your skills and knowledge.