I have a huge gap in knowledge for so many things that I interact with on a regular basis, but that I don't actually need to understand well in order to meet minimum job expectations.
This seems like a good book to address network basics. Sadly, I'm a huge procrastinator, but this seems especially important for me to address.
Books that have been in my backlog for years: Database Design for Mere Mortals, Designing Data-Intensive Applications, Building Secure and Reliable Systems, Writing a Compiler in Go, Crafting Interpreters.
All books that I know I need to read, but I just can't get around to it because there's no immediate reward for me, as someone who doesn't have to worry about any of these days in my day-to-day duties.