Try looking at things with a growth mindset instead of fixed mindset (Google it if you want to know more about this topic). It doesn't sound like low IQ at all

Try looking at things with a growth mindset instead of fixed mindset (Google it if you want to know more about this topic). It doesn't sound like low IQ at all to me. Besides the already stated ADHD, it might also be an issue of motivation. If something is not fun enough or you aren't motivated enough by other means, it can be really hard to focus on something. Even if something makes sense on paper and is something that you should like, etc. Try focusing on what you are really passionate about and what energizes you during work. And continue learning and getting better by putting more time in it. Maybe you are focusing on something that you don't really enjoy. You sound very doubtful. Or maybe you just need more experience. Don't worry if you are slower with coming up with ideas. It's not that important to have an answer quickly most of the time. In real life (non-interviews), you often have time to think things through and find the right answers by your own means. And intuition comes naturally with more experience.