Hello. I was testing my world in the 1.13 snapshot and i realized that i dont get the prefix next to my name that i created. I used NBT Explorer.

The prefixes are very helpful for server staff ranking systems, and not having them will Destroy Ithem on vanilla servers.

The NBT Tag can be found here:
World > data > scoreboard.dat > data > teams > "team name" > prefix:
suffix: