Single-member LLC owned by a minor. Does the minor have to file taxes?

My friend‘s daughter is a musician and has a single-member LLC. She says the LLC’s profit and loss were reported on her husband’s return, not her daughter’s. Did she make a mistake? Is there a $ threshold of LLC income below which this is ok vs not?

I see a lot of articles about filing requirements for minors with W-2 wages, or adults with single-member LLCs. I’m not clear about the rules for minors who own an LLC. TIA!