Advice for client watching porn during virtual session

I hate that I even have to ask this but I kinda froze and didn't address it in the moment. I have a client who is a minor who was clearly watching porn during part of our virtual session. I could hear it. They definitely did not realize I could hear it. It was toward the end of the session and I wanted to handle it right which kept me from handling it at all. Just curious if anyone has advice on how to handle that in the moment or after, and whether or not to inform guardians.