Why does this happen?

Thank you for letting me know. If the reset doesn't work and you're unable to get it working with an external drive then my suggestion would be to either try playing it via the Cloud or see about setting your console up for a repair if it's still under warranty.

My xbox live account has been banned. I have no idea why it happened. I do not recall doing anything that would merit such actions. Is it possible that i have been hacked? Does this happen to others? I did notice that my avatar has changed and have
had problems logging in before the ban appeared on screen. Can someone please tell me what happened and why?

The Avoid Player option only reduces your chance of being matched with that person, it doesn't eliminate it.

If the game you are playing as a smaller community, then the odds are you are going to be matched up with the same people.

Thank you. If it's a Series console then the issue may still be the same but it would be a little more difficult to resolve as you may need to get the official Series X/S expansion drive.

However, what I'd like you to try from here would be to cancel the install then try a factory reset on the console. There's an option to keep your installed games and apps and your saves will be safe on the Cloud. You can do a reset via the Settings menu. Please make sure you know the email/password for your account.

Try using a different browser or clear the cache of the browser you're using.