Yep, you had entered a hacked lobby.
But it doesn't seem like they were unlocking stuff but boosting big time, everyone with a 99 in kills and deaths is a clear participant of this to me.
I hope you had reported all of these people with the in-game report system, else, do it in the support site, the vid is a clear proof of hacking, tho I'm not sure you can post it here. But cheers on recording it, the only time i entered a hacked lobby I was shocked enough to forget I could record it or take a screenshot of it (it was on PC anyways) and the lobby creator was bragging on how much we were enjoying the free ranks up... some people really needs a better hobby I swear lol.
Thank you for posting your concerns here. I understand how frustrating it may be to unknowingly join a modded lobby and have your stats altered. The best thing you can do is to immediately leave the lobby and report any players you suspect of cheating via in-game report tool. Please refrain from posting other players gamertags (naming-and-shaming) as it violates our forum policy. If you have not violated the security enforcement, you should be okay. We are unable to say 100% as these are matters our security team handles.
Can you please private message me the following information:
Rank before altered stats: