Moving out from lurk mode and started posting here, I thought I might share with you my experience with this type of Bing issue. Please note this is still ongoing, but seems to solve at least my kind of problem with Bing.
Problem: suddenly, "site:domain.com" returned zero results, with the message "some results were removed".
Solution (my case): My site is quite popular in Google and since the start of 2022 I had thousands of bad links pointing to my site from hacked sites. But not only for my site, it was the same for all competitors. So we're all linked from lots and lots of hacked (legit) sites with scraped content.
I try to stick to the rule of not touching the disavow tool and since I got pretty good natural, organic links in the same period, I just ignored the bad ones. In my case, Google was smart enough to mitigate the attack. I still get them anyway, there's no stop to this. Most of the links go 404 as soon as the site realises it was a hack.
But Bing is not that smart and it simply dropped my site. I also saw some of my Google competition being delisted from Bing as well. After sending the usual email to Bing support and got no reply, I went to the Bing console and starting disavowing links. I had links from around 1500 domains and I selected only 10-15 links which I recognised and simply disavow the rest.
So far, it seems to work as the site slowly rebuilds in Bing:
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Since the disavow it took around 2 weeks to see the changes (yeah, I moved slowly because sometimes I forget about Bing existing in the first place) :)
And to not forget, I also updated my sitemaps with the new ones.
Hope this helps! Good luck!