Nickname Easy

Couldn't find a good Forge mod for nickname management so I created one for the community <3 (UPDATE: Now works on Folia and Paper 1.21.8)

Nickname Easy is a lightweight Minecraft Forge mod allowing players to easily set in-game nicknames, supporting both single-word or first-and-last-name combinations. It fully supports the Cyrillic alphabet, configurable commands, and custom reply messages with color formatting. Perfect for personalizing your Minecraft server with simplicity and style!

You can easily use it as a dependency without including API files, here's an example on how to get player's custom nickname using persistent data: