The worsening has definitely been progressive over the last 10 years, but I feel there were some sudden changes over the last couple of months that make it a lot less usable than before. For some searches I get the feeling that there's some kind of whitelist of websites that are included in the search and a huge part of the internet is being excluded. I was looking for a pretty basic diagram some days ago, nothing too obscure, and there were maybe three dozens of results in the image search. I also find more and more pages that are obviously badly translated English content when I search for German terms. I never had that problem in the past. The same goes for product testing. I tried to find a good office chair, but the websites that claim to test different models obviously try to lead you to one specific product. The texts feel like auto-generated content to simulate real articles about the products being tested, but at the end chair X, and only chair X, is the right one to buy.