Android 12 has several visual changes, the biggest of which is Material You. Material You's dynamic color feature uses Monet, a new theme engine introduced in Android 12 that is currently only available on Pixel phones. It extracts colors from your wallpaper, generating rich color palettes. Applications can apply these colors to their UIs in a variety of ways, which is what applications incorporating Material You usually do.
However, other aspects of Material You include a redesigned quick settings menu, in particular a controversial change to Internet Quick Settings tiles. To turn off Wi-Fi on your Android 12 device, tapping Internet Quick Settings will take you to another menu, where you can toggle mobile data, Wi-Fi or select another Wi-Fi network. To be honest, I do prefer this change, but I can understand the frustration because it introduces extra buttons. If you want to get back a dedicated button to switch your Wi-Fi, Mishal Rahman shared a command on Twitter that you can retrieve via ADB execution commands. There is also a Tasker project to restore wi-fi quick switching. It adds an "Off Wifi" toggle in quick settings, making it as easy to turn Wi-Fi on and off as before. You can also hold down the button to open Android 12's new Internet panel and see all your Wi-Fi networks and mobile data in one place. In addition, you can double-click the switch to turn on Internet Settings.
Google offered the following explanation of why it made the change in Android 12:
With this new design, you can quickly switch between Wi-Fi and cellular connections by selecting your cellular network from the new Internet panel. From our user research, we found that most users turn off Wi-Fi to force their phones to connect to a cellular network.
This is usually done when the Wi-Fi connection is poor and there is no other way to explicitly connect the phone to the user's carrier. Users who turn off their Wi-Fi often forget to turn it back on, which can lead to the overuse of mobile data. Our research has shown that this has been a pain point for users, so we decided to address it with this release. With the changes we're making, customers with Wi-Fi connection problems will be able to switch to their carrier with just two quick clicks. In our user research, long-term Android users admitted that the changes took some time to get used to, but once they did, they found that panels gave users a more intuitive and easy way to solve their Wi-Fi connection problems while reducing user errors and unintended consequences.
The company also announced that a future Pixel feature will reintroduce the ability to access Internet Settings from the lock screen without unlocking the smartphone.