The Fourteenth Amendment addresses citizenship rights and equal protection of the laws.
People who are born male and identify as male are allowed to use their preferred gender identity's bathrooms. People who are born female and identify as female are allowed to use their preferred gender identity's bathrooms. People who are born as male and identify as female are not always able to use their preferred gender identity's bathrooms. People who are born as female and identify as male are not always able to use their preferred gender identity's bathrooms.
For example: Laws are being passed in Florida and Texas stop transgender people from using either their preferred bathroom or bathrooms altogether.
This is a clear violation of our 14th amendment right.