Videos created on my iPhone 12 are showing as "Unsupported Video Format" in OSX Photos

I have already looked at this old thread which hasn't helped - https://discussions.apple.com/thread/7668769 ...Essentially, I'm having this problem and someone else I know is having the same problem. Why does OSX Photos tell me that my iPhone photos in iCloud are unsupported? Videos will not play, or if they do play it is choppy and might not finish.