Speaking from my own experience owning a small, non-commercial website, the drop in organic traffic (human visitors) is more like 50% over the last year.
My website has been scraped many times, and continues to be scraped, by various bots and other agents, including the major, so-called "artificial intelligences". I expect that my drop in traffic is due mostly to people asking questions that are answered on my site but reading only the summaries provided by AI and never checking for the details that might be found on sites such as mine. I suppose, why bother to visit a real website when you can get a short, half-but-sufficient answer from a convenient large language model with a cool name?
The information on my own website is based on my own research (unless stated explicitly otherwise) and is covered by a Creative Commons Attribution Non-Commercial Share-Alike copyright. Recently I directly queried ChatGPT with a carefully worded question based on some information from my own website. The answer I got was almost word-for-word from my own website, with not a single reference to the source. Not one credit or reference to my website.
In spite of regular and frequent updates, revisions, and additional material to my website, legitimate (human) visitor traffic has declined by at least 50% since about a year ago. One wonders why anyone would continue feeding the AI bots.