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

Off the top of my ancient head:

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

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.

What were your fantasies when you reached puberty?

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

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

Obsessing about clients outside of work hours.

Deion Sanders is home in Texas dealing with an unspecified health issue - NBC Sports

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.

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

China's Tianwen 2 spacecraft sends home 1st photo as it heads for mysterious 'quasi-moon' asteroid - Space

General Introduction to Boundaries from Panahi Counseling:

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

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

After trying to buy Ilya Sutskever’s $32B AI startup, Meta looks to hire its CEO - TechCrunch

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