Since I pretty much only use Google Books for public domain books, old magazines, and newspapers I haven't noticed any problem with it. Maybe it's not as dead as this person thinks.
No the search results went from pretty good to absolute garbage https://bsky.app/profile/adamnemecek.bsky.social/post/3mdbup...
This was addressed in the post, I'm sure you just missed it when you read it:
"But a few days ago they removed ALL search functions for any books with previews, which are disproportionately modern books." <emphasis mine>