my mother said that the wishes she were bisexual. she had a girlfriend for a year, when I was 7 years old, but she didn’t like it. I don’t know how to react… idk if she’s being biphobic in a certain way

I don’t see how that’s biphobic, you can wish you were a certain way as long as you’re respectful about it.. I wish I was a millionaire! But.. Not happening for me. ^^
Your mother sounds like she’s being honest, she wishes it was something she could experience. As long as she’s not harassing people I think it’s fine. :3
With love,
                Bi-Positive.