Problem/Motivation
Looks like Microsoft has silently removed support for the ping API. There is a blog post describing this https://www.ctrl.blog/entry/sitemap-ping-indexnow.html and if you simply use curl -I "https://www.bing.com/ping?sitemap=https://www.example.com/sitemap.xml" on the command line, you see this problem right away. This is not an issue with this module, but it's being affected.
The simple sitemap module is seeing the same problem, see #3255714: Bing 410 Gone
There is a new service IndexNow (https://www.indexnow.org) which could be integrated as an alternative? But there is already a separate module which may be helpful: https://www.drupal.org/project/index_now/