banned, don't know why :(

For information about suspensions, you'll need to go to http://enforcement.xbox.com

The enforcement team are the only ones who handle suspensions and they do not use the forums so no one here can tell you. The only information they will give you is what is provided on the enforcement site. They will not give specifics.

Another spammed, prewritten non-answer.

I guess I just have to assume Xbox banned me for ........... something.

I surely won't do something again!

generally the report system is now being used by other players as a tool to get back at players that they cant win against, i received a communication ban on my account 2 days ago after a few days playing only competitive games, the harassment ban will be
ending at a different time to your original suspension so you just have to wait until its over becasue the appeal system for the enforcement team is a joke and nothing ever gets overturned even if you can prove otherwise

Its till year 9999, so will I just be unbanned at some point, doesn't seem like a ban appeal review would be very helpful

This seems like a permanent suspension. An account suspension completely blocks the affected account from being able to sign in to the Xbox Live service for the duration of the suspension. Account suspensions are issued for a specified duration, often of
1, 7, or 14 days, though egregious or repeated violations can result in a permanent suspension.

To check your suspension: https://enforcement.xbox.com/Enforcement/ShowEnforcements

For more info on case review: https://enforcement.xbox.com/home/howto#sub-topic0-6

The enforcement team are the only ones who handle suspensions and they do not use the forums so no one here can tell you. The only information they will give you is what is provided on the enforcement site. They will not give specifics.