It often feels like I know too little for my role. For example, in distributed systems, in networking, in computer science, even in my main programming language. And that results in a strange feeling of guilt for doing something unproductive.
Outside of business, you can consider learning how to cook a great meal, or learn a martial art for recreation and mastery.
That's a very strong sign of impostor syndrome. Nobody knows everything. Be curious and inquisitive, but try not to obsess.