Android Messages’ automated spam protection feature has been enabled on some Android devices. Google confirmed that the spam protection engine will start analyzing all incoming messages if the “Spam protection”” option is enabled in the app’s Advanced settings. Android Messages users who will receive the opt-out spam detection feature update will also be able to block and report spam messages. The feature will temporarily store all the phone numbers of people who send you text messages as well as the times they were received. Google said that none of the contents of messages sent by the device’s owner would be delivered to its servers.”
Source: https://www.bleepingcomputer.com/news/google/android-messages-can-now-detect-and-block-spam/