Right, but TIOBE doesn't measure usage. It measures popularity by way of search engines. As people blog about their favorite new feature of C++20, it drives interest.
The claim at the top of the page is that "The ratings are based on the number of skilled engineers world-wide, courses and third party vendors." However, the details show that it really is just a single search term across a variety of search engines. Maybe they used to have an intern read the classifieds at the back of the Communications of the ACM or something.