Infection ban?

I was banned for greifing and I am looking at my theater and don’t find any incredible evidence for this. If you could tell me why I would thanks you. Also I got kicked because I kept falling off the map by accident in the game before. Could you help me ?

How long is the ban?

It was probably because you fell off the map. It is understandable that it was an accident, but in most gametypes it would be an issue that could ruin the game for others.

There is an official ban thread pinned in the support forum. You should use that thread for all questions and discussions about being banned:
https://www.halowaypoint.com/en-us/forums/e0d9938206f04a598ce84f2c8cadce02/topics/the-official-halo-5-why-was-i-banned-thread/19fa6556-e0b1-4248-b817-b3a99d0af5bf/posts