Basic info:

• Node.js version: v14.2.0 (local), v10.21.0 (Runkit)
• jsdom version: 16.3.0

Minimal reproduction case

let { JSDOM } = require('jsdom');
let doc = new JSDOM(`
    <h2>Heading</h2>
    <h3>Subheading</h3>
`).window.document;

console.log([...doc.querySelectorAll('h2,h3')]); // => 2 elements
console.log([...doc.querySelectorAll(':matches(h2,h3)')]); // => 0 elements

Runkit live demo

How does similar code behave in browsers?

In Firefox 78, which supports the :is() selector, both queries result in two elements. Safari, for :matches(), and Chrome, for :-webkit-any(), give the same result.

I know things are still in flux in regards to the :is() and :where() pseudo-classes, but since the :matches() selector exists in JSDOM it is suprising behavior.