Why am I getting banned

I will be playing halo 5 on arena then all of a sudden I will get put in the main menu and a message pops up saying your fire team has changed then I will go to play anther game then it says an banned can any one help me

Please direct all questions pertaining to bans to the pinned official ban thread in the support section:
https://www.halowaypoint.com/en-us/forums/e0d9938206f04a598ce84f2c8cadce02/topics/the-official-halo-5-why-was-i-banned-thread/19fa6556-e0b1-4248-b817-b3a99d0af5bf/posts