Did RMA on my PC and, Gametag banned?

hello guys

I did RMA on my Ryzen 2700x some weeks ago and i set up an old PC to play FH4 until the RMA finishes, but when i log in i received the notice: my gametag was banned

where i can found a clue why and when i got banned without a PC? (i dont have xbox one or X)

here’s the ban message Imgur: The magic of the Internet

You can submit a ticket on the the official support site: https://support.forzamotorsport.net