I have just Googled this issue and found this thread of comments about exactly the problem I am having. I upgraded to Ventura on my MacBook Pro a few weeks ago (I was delaying an upgrade as still using 32 Bit software!). I did not have this problem prior to upgrading when I was using Mojave.
I uploaded RAW files taken with my Canon 5D Mk3 today. I have exactly the same problem that as soon as I edit them, when I return to the general view screen they are blurred - only the edited version not the untouched ones. I did not have this problem when using an older version of OSX.
If what others have said is true - in that this is a recognised problems of well over a year - it is totally ridiculous. I should not have to purchase expensive 3rd party software simply to overcome a bug from Apple on kit that is incredible expensive.
As a footnote, I did try the fix of rotating 90 degrees in Edit, saving, re-entering Edit mode and then rotating back again and saving but the image was still blurred when I returned to the general view.
As the original post is well over a year ago from 2022, has anyone been able to discover a fix or patch to resolve this? Thanks everyone in advance - I know we are all incredibly frustrated by this!!