For me, I wouldn't mind knowing they are AI. For me, I have a lot of past trauma that I just don't even really think about which I need to work through, but I'm pretty good at analysing events and patterns in my life once I sit and think about them. So an AI therapist would be kinda like guided jounaling with different calls to action based on therapy style.

The lack of human element might make people more honest and earnest about treatment, too. When I was younger, I wasn't really honest in therapy - I didn't want the therapist to think badly of me and I was afraid I'd be locked up if I talked about dark stuff. OTOH, AI therapy might increase paranoid avoidance of therapy since transcription of the session would be instant. There would have to be huge protocols for privacy.