I’m not American and am still learning about this, but from what I understand, by Democrats not fully acknowledging that biological sex can’t change through surgery or self-ID alone, the rights at risk might be:
The right to privacy in female-only spaces like bathrooms, changing rooms, and shelters. Many women expect privacy and safety in these spaces, and allowing self-ID could make some feel vulnerable, especially if the person still has male anatomy.
The right to fair competition in women’s sports. Title IX was created to protect equal opportunities for girls and women, including sex-based categories to ensure fairness. Transgender women who’ve gone through male puberty may retain physical advantages, impacting a level playing field (as has been shown on a number of occasions now).
The right to freedom of association. Some women want female-only spaces for empowerment and solidarity.
I respect everyone’s right to live authentically, but think policies should better balance these rights with women’s comfort, safety, and fairness. The Democratic stance felt ambiguous on this issue, leaving many who do not buy into the concept of gender ideology concerned that these rights may not be clearly defined and protected.
The above of course would affect all biological females, adult or child, in answer to your question.