Anyone who uses Google Messages is probably logged in with their default Google Account in it. Many people have two or more Google Accounts on their Android phones. Google Messages easily allows switching between these accounts. Google also allows to use Google Messages without an account, but previously it didn't warn users what functionality they could lose if they use it without an account.

Google Messages in beta has been quietly rolling a new change which notifies users about what features will not work if they sign out. It also notifies users when they switch accounts because some features are account based. I have the feature enabled in my Google Messages already. Here are some screenshots - 

As you can see in the screenshot, when you tap the "Use without a Google account" option in the account switcher of Google Messages, you will see first screen which show that - "Not available when you sign out - Magic Compose and Device pairing". You will lose both features as they require a Google Account to work. Additionally there is also an option for users who have profile discovery feature enabled in their Google accounts. It says "Stop profile discovery for this number (recommended)" and is enabled by default. You can uncheck it if you still want to be discovered through profile discovery feature which will allow other users to see your profile picture and name. 

But turning off this option has also some trade-offs as it says in the screenshot that "People who know your phone number may not be able to find you in Google products and services". So the choice is yours. The screen in second screenshot appears when you switch between Google accounts in Google Messages. It just warns about losing two features - Magic Compose & Device pairing. Both feature seems to be account dependent so it's possible that they may not be available in your other account if you switch account.

This feature seems be available already for some people who use the latest Google Messages beta which have been already started rolling out this week. 

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