What should I do about a player I think cheated during character creation?

I'm DMing my first ever campaign, and I've never been involved in a campaign until the one I'm in now but I've watched some on YouTube so I know the core essentials of the game but not much else. Most of the people I'm playing with have played a lot, and one of them told me that one of my other player's is way overpowered for the point we're at. He's a level two bard and he has a deck of many things (which he started with), two skills with expertise, five with proficiencies and the rest have half proficiencies. He also started with an unlimited amount of "fantasy weed" which I wanted to do something about anyway but another player ended up stealing it from him and destroying it so that doesn't really matter. Is there anything I can do to nerf him?

Edit: For clarification he wanted to sell the fantasy weed to NPCs to get a lot of money

Edit 2: He made his character sheet before the campaign and I didn't see it until he added it to the campaign on DND Beyond. The only character I helped make/saw before the campaign was one of my friends who had also never played DND before which retrospectively was probably a pretty dumb choice.

Edit 3: I think he's using 5.5 while me and the other player didn't know that so that's why he has the proficiencies and expertise