Discord.Net/docs/guides/guild_events/getting-event-users.md

uid	title
Guides.GuildEvents.GettingUsers	Getting Guild Event Users

Getting Event Users

You can get a collection of users who are currently interested in the event by calling GetUsersAsync. This method works like any other get users method as in it returns an async enumerable. This method also supports pagination by user id.

// get all users and flatten the result into one collection.
var users = await event.GetUsersAsync().FlattenAsync();

// get users around the 613425648685547541 id.
var aroundUsers = await event.GetUsersAsync(613425648685547541, Direction.Around).FlattenAsync();