What are some signs that a therapist may have poor boundaries with their clients?

Session-expressed curiosities about client details not relevant to the therapy.

Failing to mention the client in supervision/consultation, out of fear the supervisor/consultant will advise return to ordinary healthy boundaries.

Obsessing about clients outside of work hours.

I'm British and I hate my glasses. Are prescription glasses better in New York City?

Sense of competition with persons who are important in the client’s life.

Frequent phoning or texting of clients to “check up on them and make sure they’re OK.”

Eager anticipation (or anxious anticipation) of the next session in ways that distract.

Why can't my adopted sister accept she is not part of my family because she isn't related? Why can't she stop calling my parents mum and dad?

General Introduction to Boundaries from Panahi Counseling:

These items can happen fleetingly, briefly, in any therapy, but if they’re frequent, it’s definitely time for the therapist to get some good, solid supervision/consultation.

Routinely going over the time limit with certain patients, compromising the time for the next client.

Why are flat Earthers made fun of when they seemingly don't exist? I have only met one flat Earther in 18 years.

Disclosing feelings, fantasies, and experiences to the client in ways not related to the work the client is engaged in.

Struggling with fantasies of deeper connections with clients, whether sexual or parental or other intense or intimate relationships beyond psychotherapy.

Serious disappointment when the client cancels a session.

Is there anything you did that you regret? If so, what is it, and why?

Off the top of my ancient head: