Safari displaying distorted or missing images

Since several recent updates in Monterey I've noticed the top image on some web pages not displaying correctly. They either fail to load and you're left with a grid of cyan and magenta lines or they partially load with heavy distortion (rather like bad TV interference from the 1960s!)

I can't reproduce and add screenshots of the latter well enough at the moment - the occurrences are random and so far I've only noticed it on news sites like the Guardian and Independent newspapers.

Similar queries have come up before so I tried all the suggestions from those posts like deleting the caches, deleting all history and unchecking 'lazy image loading' in the Develop menu. Still no joy - any help appreciated. Chrome is fine ... of course!