Think I may have a player who built a game breaking character, help?

Ok, I might be overreacting, and I hope I am. My wife has been hyping up her brothers new character he has made for COS that we will be starting in a few weeks. I am by no means a DnD expert and I'm still trying to learn all of the rules.

Edit: its a Champion fighter, not a gunslinger.

Anyways, he wants to play a ~~gunslinger~~ build using a fighter in the 2024 rules and his list of features and traits is longer than the campaign is! (Not really but theres alot of stuff in there.) I really just need some feedback. Mainly Im concerned there is a build hidden amongst the features and traits that is going to break my campaign. The character sheet I have is a bit outdated. He will be sending me an updated one hopefully tomorow.

I thing this is the right link. [Google drive gunslinger ](https://drive.google.com/file/d/1iKhpoVkSQDypwUinrMUqPuxi6EAgLePj/view?usp=drivesdk)

Edit: turns out I was overreacting. Thanks for the feedback everybody. I blame my wife, she likes to push my buttons.

Edit: 2. The revolvers and the Critical Role feat are indeed a problem. Thanks for pointing those out.

Edit 3: The revolvers were non negotiable for him, so he's just going to pick something else. Big thank you to those who were willing to discuss things with me and pointed out some major errors.