At the end of May, Google Authenticator received its first update in a year, which hid your two-factor codes
Google Authenticator version 5.20R4 removes the "Tap to Reveal PIN" feature so that when you open the app, you'll immediately see all your two-factor authentication codes in a list.
Most likely, the "Click to" functionreveal" was Google's attempt to add another layer of security to make it harder for those in close proximity to you to look at your phone screen. On the other hand, the codes already change every 30 seconds, so it is unclear how effective this measure was.
In addition, this update never appeared on iOS. There, it asks for Face / Touch ID authentication before showing the codes.