Unfortunately I can’t read the original text myself but the machine translation I looked at used the phrase “5G messages” so I interpreted what the Redditor was doing as providing clarification as to what that is in context (“RCS”). Per the document you pulled up, I can see why it would just be called 5G Messaging or something like that, not technically true, but may as well be true as I didn’t realize the GSMA had also mandated it for what they’re calling their “Universal Profile”.

> Operators are free to decide whether or not to implement RCS within their 4G networks. However, the 5G standards mandate the implementation of RCS in 5G networks and devices.