The new logo is a cleaner take on the original, with not much changing besides the overall shape and design elements. If you haven’t used Play Books in a while, returning to find this icon ...

This icon definitely did not need the four-color treatment. It joins the new icons for Play Games and Play Console. This icon is rolling out with version 2023.5.30.0.1 of Google Play Books on Android.

More info. I don’t think I’ve opened Google Play Books in 7 or 8 years, but that streak has since ended, as I did so today to check out the new logo/icon that’s rolling out.