I don't go on Substack, I avoid Twitter like the plague, and I try to avoid articles that give their take on what Buffett said. Like everything in life, it's usually better to go to the primary source. I've got Buffett's chairman's letters in the hardbound book and it's a great learning tool. It seems all media is moving towards shorter, click baity content. Twitter is the worst for the written word, and Tik Tok for video. Maybe you should make a conscious effort to move in the other direction towards long-form content.
There are legendary investors who have written books (Peter Lynch, Ben Graham, Phil Fisher, Phil Caret, Joel Greenblatt, Einhorn, Tillinghast, Howard Marks) and I think those are great sources. I read a lot of biographies. Currently I'm reading one on Marvin Bower (responsible for taking McKinsey from two offices to an international powerhouse). In the past I've read books on a particular industry (shipping) and I have one in my queue about graphene now. I don't know if I'll ever use the knowledge, but it's easier to just keep accumulating knowledge and then having it ready if something comes up then to pass up an opportunity because by the time you get up to speed on something the opportunity passed.