When I create a web component (I'm using lit/lit-element in particular) that dispatches a custom event, I can:

Dispatch the event from window:

const evt = new CustomEvent("my-custom-event", {detail: "some-data"});
window.dispatchEvent(evt);

Or dispatch the event from the web component itself (this):

const evt = new CustomEvent("my-custom-event", {detail: "some-data"});
this.dispatchEvent(evt);

Is there a reason why I may want to do one versus the other?