I also noticed how it suddenly went from great to crap.

But the real reason I think is ironically AI. It used to be that you could easily crawl the web, but after the AI craze, images suddenly became valuable to crawl and every website gets bombarded by scrapers, and are adding more and more countermeasures to make it more difficult, so tineye's own image scraper probably can't compete with them and so can't find any new images