Safari has begun incorrectly displaying images on Web sites

Safari has begun incorrectly displaying images on Web sites (e.g., pictures in an on-line newspaper). The image comes up correctly, then turns to incorrectly mapped pixels. Those same pages work just fine in Firefox.

Is this a new problem for Safari? It's been a decent browser, but now that it messes up images (usually only the first one on a Web site) I'm moving to Firefox. Could it be related to the support for older versions of iOS: I'm on an older MacBook Pro that can't be upgraded past iOS 12.

[Edited by Moderator]