Unfortunately, PA is often done secretively without the other parent realizing its invasiveness until their child is more fully indoctrinated. Here are a few signs of Parental alienation:
Your child distancing themselves, questioning your motives.
Increased anxiety when your co-parent is mentioned.
Parentified language, saying unusually hurtful things to you and/or acting out in other ways.
Error on the side of caution and immediately seek the support of mental health and legal experts to guide you through your options.