I don't think Google and Bing AI fully understand how classifieds sites work. No classifieds platform keeps expired ads as permanent pages, they automatically expire and are deleted if not renewed. Yet both Google and Bing still treat some of my ads that expired 2–3 years ago as if they were live pages they "can't find." That's ridiculous. Those outdated references should be actively purged from their indexes, and only current pages should be crawled and indexed. Otherwise, search engines end up claiming I have millions of "missing" pages, when in reality, those pages never existed in the first place or were intentionally removed.
Do you use structured data with the end date as part of the feed? It would be disappointing to give them that info and have it ignored. I see lots of missing pages that they report as being "not a problem". Websites change their content for many reasons. Classifieds like yours are a pretty good example.
Grok suggests adding <meta name="robots" content="noindex"> to every expired ad page, which should prevent indexing. I'll implement that. The core issue is that search engines continue to crawl and display 2–3-year-old ad pages that now return 404 errors. Despite the HTTP 404 status, they seem to ignore the signal and keep these outdated links in their indexes.