Either a separate mod or an option in nametags mod, when enabled, depending on the server you're on it'll give you options to select the mode you want to show tiers in. When you select a mode, if someone has tier tested in that mode you picked then it'll show up in their nametag. For example: "S | xFlxme"
I have developers who can easily develop this mod and make it compatible with Badlion Client.
For those who don't know what tier testing, you basically get ranked based on how you play in a 1v1 against another player. It's done on servers such as Hypixel, Minemen Club, or Bridge Scrims.
It'll work with .gg/tiertests