I was thinking that perhaps she didn't like something you commented (that is probably the most common reason people block others on social media), but if it was years ago and you only got blocked recently, that would not make much sense. I would just ask the T. I really think most therapists who use social media (including strictly business pages) do not manage them super consistently and democratically. I know this not only from observing but also because one thing I do as private work is managing professional social media for clients. They pretty often ask me to do things and deal with other users in ways that do not make any logical sense to me and are quite discriminating. This includes some mental health professionals. There is also the added layer if someone else is handling the pages and they have freedom to do things on it, they might not always adhere to policies the owner would have, strictly. Why is that? As I mentioned, IMO (and experience) it can be many things, even just as ordinary as an error or unintended click. The latter happened to me a couple times and it resulted in deleting an important contact, purely by mistake, which I did not even notice until much later. Other thing that happened, when handling many social media accounts from one computer, is posting something on the wrong page, for the wrong user, because I was not logged in to the correct account. That can be even more annoying even if it gets deleted immediately. None of these were in FB for me but others where it is easier to make mistakes, but can happen.

I can easily imagine jealousy from a Ts spouse as well, especially if they are in situations like you describe, know the client well etc. But I agree with you, it should not be managed in this way. If they choose to handle the profession in this way, which is a bit unconventional, I think they should be super responsible for not acting out impulses that may come with the nature of the situation. This is why I would ask the T directly, instead of speculating and getting too upset. If you don't want to express the upset, could maybe just say something like "You know I sometimes look at your professional FB page. I've just noticed recently that I'm blocked from it. Do you know why?"