When I want do do some small DOM manipulation I can now just use standard Javascript, jQuery went from providing an essential service smoothing over browser differences to just providing better syntax in that space. When I want to do more, often React or similar is a better fit. So I end up barely using jQuery anymore.
That said, I can imagine quite a few scenarios where it would still be the right tool for the job.
No, it's because modern Javascript has now solved the problems that jQuery originally solved. Chiefly DOM manipulation and AJAX requests. It's still a fine library, but jQuery is just no longer needed.
That said, I can imagine quite a few scenarios where it would still be the right tool for the job.