There’s only been about 700 yacy peers online in the last 30 days which is pretty low for a “crowd sourced” search engine, especially when many of those are, I think, temporary peers that come and go. It looks like it has only maybe 200 “master” servers which wouldn’t be nearly enough to keep up with the Internet these days.
The good news is that if there’s websites / urls that you care about you can point your own yacy instance at them and schedule the crawls to keep up with content changes.
I remember reading about yacy some years ago and now that I’ve bumped it into again it’s sparked my interest. I may stand up a docker instance and play with it for awhile. If nothing else it could make a very useful “arrrrr” search engine.