WS-116521-6 is PlayStation's way of saying the service you tried to use is temporarily down for maintenance. It appears when signing in, opening the store, or starting an online game, and it means the problem is on PlayStation's side, not in the console.
If the status page is green and other devices on the same network reach the internet normally, try a wired connection instead of Wi-Fi, and check whether a different account signs in on the same console. If one account fails while another works, the problem is with that account, so check its sign-in details and any messages from PlayStation about the account.
How long does PS5 maintenance last? Most maintenance windows last from under an hour to a few hours. The service status page is the only reliable source for when a specific service is back.
Can I play games while WS-116521-6 is showing? Yes, for games that do not need an online check. Single-player games already installed on the console usually still work, while online multiplayer, the store, and cloud saves wait until the service returns.
Is WS-116521-6 a ban? No. A suspended account shows a different code and message. WS-116521-6 states plainly that the service is under maintenance.