Marketplace repayment advice

At the beginning of 2023, my brother, mother, and I were enrolled in a Healthcare Marketplace plan. My brother got a job in February that pays about 75k. I forgot to opt him out of Marketplace, and now I’m pretty sure we’re going to be hit with having to repay the entire subsidy since I believe he makes over 400% of the Federal Poverty Level for a single individual. Based on what I’ve read through so far, the only way to remedy this is to reduce his AGI. From what I understand, the only way to do that is for him to contribute to his Roth IRA or HSA. Since the maximum contribution he can make to his Roth is 7k, and I have no idea how an HSA works, are we totally screwed? I think he’d have to reduce his AGI by like 20k in order to fall under the 400% poverty level, because as an individual the amount is 14,580 and he made 75k this year.

I don’t know anything about taxes and i’m freaking out at how stupid i was for forgetting to opt out. I’m terrified this will cost us like 20k because that was pretty much the total of our healthcare premium in 2022. Please please help me and please be gentle with your words because I am on the verge of a break down.