The new APK decomposition of Google Messages app version 7.2.203 for Android reveals powerful text suggesting changes to the default SMS client for Android. Google was responsible for the next generation of SMS, called RCS, and its latest effort was to provide end-to-end encryption for instant messaging services.
Perhaps due to this new secure feature of Google Messages, Google has disabled the app from working on “unauthorized devices”. This is due to the decomposition of the APK. XDA-Developer This reveals a series of texts, suggesting that phones that aren’t certified to work with Google mobile services will stop working in messaging apps.
An uncertified device is a device that is running the Android OS but has failed Google’s certification process for Google mobile services. This may include devices running unofficial modified software, non-GMS certified Huawei devices, or devices with unlocked boot loaders. These devices do not meet the requirements set by Google for GMS, which can compromise the security of online services such as RCS support for Google Messages.
Google has not yet approved the change. Given the March 31st date, it seems that Google will notify affected users of changes when notifications are triggered by future updates to the Android Messages app.