It depends on what kind of therapy your T is talking about. Psychoanalysts almost all undergo lengthy therapy, which is not IF they have mental health issues, but simply because that's often part of the training. Other therapists though usually don't share that info with the client, it's not part of the training or required for many, and certainly not something to share on the first interaction. In a way it's personal stuff. And can make client worried, for various reasons. This is not to say many therapists don't have mental health issues cause they do and many also take pills. But sharing it, it really depends on the particular form of therapy and the point in therapy when it's shared.