Logo by Voxelstice, the "Talk" icon is from game-icons.net.
(Btw, if you have light mode, you wont be able to see the icon.)
This is a custom chat system in Roblox. Model can be taken from here.
As of now, its currently under construction.
If you find a bug on the custom-chat. Either take the module and fix it yourself or report it on the issues page.
If you want to set this up, consider reading the guide.