Pings IndexNow for the given URLs, telling participating search engines (Bing, Yandex, Seznam) that the pages have changed. The property needs an IndexNow API key and a published key file: check get_indexnow_settings first. If no key is set: 1) call update_indexnow_settings with generateKey: true; 2) publish the returned keyFileContent as a plain-text file at the returned keyFileUrl (the root of every host you submit URLs for); 3) call submit_indexnow_urls again. URLs are grouped by host before submission. Up to 100 URLs per call. Note that the usual 202 response means "accepted, key validation pending", not delivered: engines fetch the site key file afterwards and silently discard the batch if it is not reachable, so do not report a 202 as confirmed indexing.