Ohhhh, shit. This is actually like, really bad.
I mean, ignore the homophobia issue, I don't recall if we've seen indications that that might be a problem or not. But even if it's not, Lin's mom is literally working herself to death to support her daughter because she married a worthless loser that was a drag on her.
She is ABSOLUTELY going to think that's what this is. Her daughter was doing fine, then she started hanging out with/dating this girl, then her grades fell and she worked herself sick getting them back up again. She is totally going to think her daughter is repeating her mistakes, whether she has an issue with her gender preference or not.