How do I learn to catch deeper problems in code review?

You catch the obvious mistakes fine. What you do not trust yet is your ability to spot the deeper design problems the senior engineers seem to see instantly. That gap is not a verdict on your talent. It is just experience you have not lived through yet, and experience is the one thing you cannot shortcut, only gather. The seniors are not smarter in the moment. They have seen certain problems fail before, so they recognize the shape early. You build that same sense one review at a time, by paying attention not just to what is wrong but to why it is wrong and what it will cost down the line. When a senior flags something you missed, do not just fix it, study it. Ask yourself: what was the signal I walked past? Keep a short running note of these. After a few months you will start seeing the patterns before they do. You are not behind. You are early in a curve everyone climbs the same way.