Burnout happens when you're forced to work without motivation. For me (same age as you), two kids and a "life" often soak up most of the motivation. I look at challenging problems in a different way: time travel. When I get fully absorbed into a tech/coding challenge I find that the entire day will slip away. For me, this used to be fun and now it's frightening because I know that a challenge will eat days of my life. For what upside? We already live comfortably. So maybe there's a part of you that doesn't want to go too deep because it's feeling like a waste of precious time.

My recommendation? Focus on tooling. See if you can create a better test infrastructure, a better developer experience for the others. Do you see another way the code can be organized to make it easier to reason about? Is documentation/code-comments lacking? Perhaps your time can be leveraged to help the others. Maybe that perspective shift can unlock your super-powers.