Searching for "google books" in google leads to https://books.google.com/ which no longer allows you to read any of your books.

https://play.google.com/books is the site to read your purchased books now.

Google search does not show https://play.google.com/books in its results at all.

Thought it was some weird personalization quirk, but seems others have had the same issue:

https://www.reddit.com/r/GooglePlayBooks/comments/15ncle0/my_books_arent_showing_when_accessed_via_website/

Bing, on the other hand, shows https://play.google.com/books in my 2nd result