Very good article -- I am having the exact same issues (I run a lightweight writing site with original writing and no ads). One thing that caught my attention is the timing. Bing blacklisted my domain from web search results on January 14 after I had no issue with them for 2.5 years (interestingly, I wasn't fully blacklisted for image results but that doesn't help me much). The rest of your article, from lack of support and information to Bing Webmaster only identifying minor SEO issues has been my experience. My site has no indexing issues with Google, Yandex, Brave, or Mojeek... so whatever it is is Bing-specific. I agree with your point on DDG too. I also had more DDG traffic than Bing traffic, and losing a smaller number of Ecosia, Qwant, and Yahoo referrals is also unfortunate. Many people do not realize how many of the alternative search tools rely on Bing's index.

Whatever is causing it -- I hope it is fixed soon.