The problem isn't jQuery, the problem is that 90% of the use cases for jQuery can now be solved with native APIs (or polyfills if compatibility with older browsers is a requirement).

The main feature is basically element.querySelectorAll (or document.querySelectorAll for the global version). The XHR wrapper can easily be replaced with the fetch API. Class list manipulation is easy with element.classList. The event listener API has also been consistently standardized across all browsers for quite a while.

There are a handful of things you might still want a utility library for (non-CSS animation among other things) but there are smaller, more specialised libraries for those. The utility belt approach of jQuery is no longer necessary.

The same is true for libraries like lodash/underscore, btw. If you target modern JavaScript environments or use polyfills and a transpiler like Babel most use cases of lodash are a solved problem -- not to mention that 90% of all code using lodash in the wild could be written using the native array methods that have been available since ES5 (and IE9).