Help me get out out of my current outdated job

A little background about me:

I’m 32 years old and have been with my current company for eight years. This is my first job after college. We use an old programming language from the 1970s that hardly anyone has heard of or used. For code releases, we rely on an internal tool that is nowhere near as advanced as Git.

I want to leave this job and work on something more modern and exciting, but I’m completely out of practice with LeetCode (though I’m actively working on improving that). Beyond that, I don’t know much—I’ve never worked with web development, JavaScript, Angular, Python libraries, or anything similar.

I’m scared to leave because, at this point, I’m used to the environment—it’s the devil I know. My biggest fear is that if I get a new job, my new team will quickly realize they’ve hired someone who doesn’t know anything, and I’ll get fired for not understanding modern technologies.

Feeling pretty down about this, and any guidance would be greatly appreciated.