voice looping suppression system is having a problem.

It seems that there has been a problem with the program's voice looping suppression system recently. We use Zoom meetings every day. The looping prevention in our system itself is working properly. This phenomenon appeared for the first time today. The other party used the laptop's built-in speakers and built-in microphone, not headphones or earphones. Our voices came through the other party's microphone, making it impossible to have a proper meeting.