Google is continuing its move to more explicitly label “RCS” in Messages with a very prominent badge noting which conversations are eligible.
Update 7/14: This RCS badge is widely rolling out to all Google Messages users.
Update 7/13: More beta users are seeing the RCS badge three weeks later. However, it’s not yet in the stable channel.
Similarly, Google Messages recently rolled out the read receipts that directly appear in your conversation list. As a result, RCS chats stand out much more than SMS/MMS threads. Neither of those changes are found in Messages for web or tablet.
Original 6/21: On the homescreen, Google is showing the Message icon in the bottom-right corner of profile avatars for RCS conversations, including group and individual. It’s a simplified version of the app logo with Dynamic Color theming applied. There’s nothing badging SMS/MMS threads.
This badge should be available in Google Contacts and Google Phone app so people would know which contacts on RCS!
Before this, you’d have to open a conversation and see if the text field said “RCS message” or just “Text message.”
From a branding perspective, Google is very explicitly associating the Messages logo with RCS. It comes as features like Magic Compose currently don’t work with SMS.
This RCS badge is presumably still being tested, and we’re seeing it on the latest beta release of Google Messages (20230615_02_RC00) today. The company previously trialed showing the updated read receipts in the conversation list. This also reflected which conversations support RCS, but in a more subtle manner. We first spotted that change in April and it has not yet widely rolled out.
Similarly the redesign that removed the navigation drawer and added those items into the profile menu was unfortunately pulled last week. 
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