The vanilla /team command wont work properly. In the command, you can set a prefix to go along with a team, for example:
/team modify Owner prefix {"text":"Owner ","color":"aqua","bold":true}
The command above works on the scoreboard like this:
It should be identical in chat, but the prefix just doesn't appear, the text only says <Doubl_A> (message). I've tried to find other ways of fixing this issue, but all the fixes I could find are either outdated, or just non-working.