Why is my website not showing up on Bing search results?

I've had the same issue in 2020, our main business website, which at the time was 15 years old, and updated regularly. It one day, just disappeared from results. Since other search engines like Yahoo and DuckDuckGo use Bings search engine algorithm, we also disappeared from from those search engines results as well. Webmaster says all pages are index, but nothing shows up. 

I tried contacting Bing webmaster support multiple times in the past, most times all I received was the exact same generic auto response email, stating to read their webmaster guidelines, which I've read multiple times, our site has always been in compliance with Bings webmaster search agreement terms.

Finally, sometime in 2021, I was able to get in contact with an actual real person from Bings webmaster support team. They told me it was due to algorithm updates some websites accidentally were removed from Bing's search listings. They assured me they had fixed the issue and that our website and our website would be searchable in Bing again, only it could take a day or two for our site to reappear in search results; stating "...just give the search engine algorithm a day or two to reindex your websites pages and it should start showing up in results again soon." I was extremely relieved after they told me that! 

Only... that was 4-years ago and I'm still waiting for my website to reappear in search results... I'm no longer holding my breath...

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Ironically... back in the 2000's while in college, I built a crappy 3-page self-hosted basic website, and for whatever reason (and I wish it didn't), it's still shows up in Bings search results to this day. 

The site itself has no value, but because it's the first site I ever built, for nostalgic reasons, I've kept this site live all these years and have renewed the hosting and domain every year.

But... I haven't updated this site since it was initially built 20+ years ago, and still shows up in Bings search results. I never even made a Bing webmaster account for it....

Can someone from Bing search support tell me the logic in that??