Sound: one phrase getting stuck over video

Hi held a live combined online meeting which I recorded. The online participants could only hear the same repeated phrase, like it had gotten stuck on top of the video and me speaking in the background (not audiable). The same was recorded. I reset the whole meeting, but the same happend.

When I've troubleshooted now with the same equipment it worked perfectly.

I've done this now for 3 years and it's never happend.

Has this happened to anyone before?
What happened and how can I avoid it?
Is it possible to recover the recording and remove the overlayer "stuck" phrase?

Thank you!

Marie