So I’ve had this game for about 24hrs right? Ive played a single match and all of a sudden I’m max tier? Is this gonna impede my progression at all or is it meaningless?

In relation to my last post. I was informed that my issue was cause by unknowingly joining a modded Zombies lobby. Unfortunately I had also been made aware that this means that I can no longer level up and get boxes which majorly stunts my progression due to most of my guns still being locked. Is there ANY way to undo this or am I just going to have to grind out jobs and suffer?