Audacity recording suddenly distorted

After spending an hour or so cleaning up a recording, I have come up against a problem. Our podcast normally includes several people in different locations and is recorded on Zoom. I then clean it up in Audacity, getting rid of over-long pauses, restarts, etc. I have been doing this without any problems with the latest recording, obviously listening to it all the time. Suddenly, I start playing again after removing a piece of the recording and it is really distorted. I hadn’t applied any effects or anything and the distortion affects the entire recording. I thought it might be the headphones, but it was the same with the external speakers. I restarted the computer and there is no change. I decided to play something from YouTube and it plays fine, so it is not the driver or the speakers.
I have noticed when I zoom in to the recording that it looks like the recording itself has somehow been distorted. I attach a screenshot which to my relatively inexpert eye doesn’t look right at all. It looks very irregular, but maybe I am reading too much into it. I suspect there is nothing I can do now apart from start again, but I would love to know how it might have happened and if there is any way to avoid it happening again! I am neither expert nor a big user of Audacity, but I have been using it for a very long time and never experienced this before.
Many thanks in advance.
Screenshot - 03_11_2020 , 12_59_22.jpg

Can*t find a way to edit my post, so I shall just add that I started on version 2.3.2 and when I came to the forum noticed there was an update so I updated to 2.4.2 on fully updated Windows 10.