I have the exact same feeling. Turning 30 was like flipping a switch for me. Since then, I've even felt like I've become more intelligent, especially in math. It's like everything suddenly clicked. I struggled with math throughout my entire school life, but now that I've gone back to college, I'm amazed by how easily I grasp concepts. I've recently taken on challenges that I always thought were exclusive to "smart people," like systems programming in Rust and Zig or building compilers.