99papa wrote:
If it is Facebook doing this, why is it that the problem doesn't exist on a PC/Windows, on other browsers
Because website programmers sometimes have to work around various browser issues and quirks. A site that works great in Firefox might work slightly different in Explorer or Edge. Some new/advanced HTML or CSS code that works one way in Chrome, might work a different way in Safari, or not at all. It's been this way since the beginning of the web. Getting better, but never perfect and no two browsers work exactly the same.
Considering how complex and bloated Facebook has become, I am surprised it works at all half the time.
In this case, Facebook has rolled out some weird change to their client-side code that seems to be affecting all versions of Safari. It's even affecting Safari on Mac High Sierra despite that version of Safari getting no recent updates.
So no, this one is not Apple's fault and we're now at the mercy of Meta.