Keynote cuts in and out during presentation

I have been using my MacBook Pro with a Panasonic projector for over a year without a problem I use an hdmi adapter to usbc for the connection. As of last month the keynote presentation suddenly goes to a black screen and then returns to the presentation at the beginning of the slide that was on the screen when the cut out occurred. If it was a video segment it starts at the beginning and replays the video.It happens inexplicably two or three times over the one hour presentation. I have tried to replicate the problem by wiggling the cords and adapter to no avail.This only occurs when I am presenting through the projector. I have the updated Keynote. This began after I updated to Big Sur if that has any correlation. Any suggestions would be gratefully received.