What is the tiny green chat bubble?

[Lady Ship]

I have an Android 11 and when I view my contacts from my phone icon some of my contacts have a tiny green chat bubble that appears and disappear at times. Can some tell me what does it mean?

 

[Morty2264]

Hi! Are you viewing them from your SMS app or from your Contacts app? That little dot could mean they're online. I'm not too sure. I'm pretty sure I saw that on prior versions of Android.

 

[B. Diddy]

Which phone? It might mean that those contacts have RCS chat turned on.

 

[mustang7757]

Which phone?