Participants in the meeting suddenly no longer visible, but instead I see myself and another partic.

The participant uses a Windows PC with the latest Zoom version. Extra update to the latest Zoom version.

At the beginning of the meeting (with 3 participants) we can all see each other well. After a short time, the video of one participant is suddenly no longer visible for the 2 remaining participants. Instead, the 2 remaining participants each see themselves in the Zoom video window of the participant we can no longer see.

The participant himself doesn't notice anything about it, he always sees the 2 remaining participants correctly.

What could be the reason for this? Webcam driver problem of the one participant?
Thanks for your help.