Thanks for your quick reply and cogent explanation. Yes, you’re right - about a lot of things.
But before I get into an extensive mea culpa, I neglected to mention in my previous post how impressed I am with ShotCut. I had tried out a number of other video editors without finding anything that was as intuitive and as well-featured as Shotcut. Thanks for contributing to this project - it’s very good.
I did get the version numbers confused. And, you were right about the GoPro - I do have a Hero7 Silver so my videos do have a variable frame rate. Not only that, after further investigation, the appearance of this VFR dialog happens in both versions (20.11 and 21.01).
However, before I started editing these videos on my new computer I had never seen that dialog. Nevertheless, it does appear that I can ignore that warning and get away without converting.
So, aside from the fact that I don’t understand why that VFR dialog is now appearing, my problem is resolved. Thanks very much for your help.