If you're wondering what Gateway Intents are, what Privileged Intents are, why your bot can't see statuses, or why your bot can't see member joins anymore, then this page should explain it to you!
if you do not know what intents are, please read this entire page
First, a short explanation of how bots work: bots can make requests over the REST (HTTP) API to retreive information and do actions, and they get real-time updates from Discord in the form of websocket gateway events. They can also fetch server members via the gateway.
Examples of gateway events you are probably familiar with are Message Create (a message was sent) and Guild Member Add (a user joined a server).