Is your feature request related to a problem? Please describe.
We want to add offline mode support, but for security reasons, we want offline mode players to make an application in our discord server and premium players can just join normally. Some of this can be achieved with FastLogin, but i don't think that the cracked player whitelist is an option.

Describe the solution you'd like
Option to let online mode players register and play, but offline mode players need to be added to a custom whitelist. We would also want them to not use any registered premium nicknames. Maybe its possible to add an custom prefix to their name, similar to what the plugin "Geyser" does to bedrock players?

Describe alternatives you've considered
FastLogin, but it would probably still be used in this context.