You can get the three-button navigation bar back on Android by opening Settings and selecting 3-button Navigation under system display options.

If you're still affected, you can fix the issue by switching to button navigation in your phone's settings, restarting your device, then switching back to gesture navigation.

Beta testing for Android's biggest redesign in years is humming right along, with Google already having released Android 16 QPR1 betas 1, 1.1, and 2 in June alone.