Deprecation Listener added for a 'DOMNodeInserted' mutation event in 14.0.0-RC2

I don’t understand why UNA should use these outdated applications. Mutation Events, including DOMSubtreeModified, DOMNodeInserted, DOMNodeRemoved, DOMNodeRemovedFromDocument, DOMNodeInsertedIntoDocument, and DOMCharacterDataModified, are detrimental to page performance and significantly increase the complexity of adding new features to the Web. These APIs were deprecated from the specification (iconSpec: UI Events) in 2011 and were replaced by the much better-behaved Mutation Observer API in 2012. The usage of the obsolete Mutation Events must now be migrated to the Mutation Observer.

[Deprecation] Listener added for a 'DOMNodeInserted' mutation event. Support for this event type has been removed, and this event will no longer be fired. See https://chromestatus.com/feature/5083947249172480 for more information.

 r.domNode.addEventListener("DOMNodeInserted", function() {}),

in

      function e(t, n) {
        o(this, e);
        var r = i(this, (e.__proto__ || Object.getPrototypeOf(e)).call(this, t));
        return r.emitter = n.emitter,
        Array.isArray(n.whitelist) && (r.whitelist = n.whitelist.reduce(function(t, e) {
          return t[e] = !0,
          t
        }, {})),
        r.domNode.addEventListener("DOMNodeInserted", function() {}),
        r.optimize(),
        r.enable(),
        r
      }