IF your ex is not happy with their psychologist, it is up to them to take this up and/or take the appropriate action (be it seeing someone else or exploring other avenues).

There are privacy and confidentiality engagements between a therapist and their client. You are not involved in this T dynamic but are merely a third party. I don't understand why you are asking about your ex and their therapy issues and trying to insert yourself within this dynamic.

You still seem very involved with your ex when you say you want to keep them at a distance. Let them deal with their issues as they wish. Trying to interfere is not appropriate.