This morning 2/4/2020 8:05am AEST I viewed one of my Facebook Pages and discovered a lot of the thumbnail images on the Facebook Page were missing/broken. This is what I saw:

I checked other Facebook Pages and they had the same problem.
I thought maybe image caching was the issue so I tried clearing the browser cache (was using Chrome) and this didn’t solve the problem. I then tested using Firefox and Microsoft Edge but both also had the same problem.
I checked the Facebook Developer status page and nothing appears to be down or reported that there is an issue.

I then went to down detector and there was a flood of comments from people reporting the same problem.

So this appears to be an issue with Facebook so there’s nothing really you can do about it. We just have to sit back and wait for the Facebook team to resolve it. Hopefully, they will fix it soon. I’ll report back when this is fixed.
UPDATE: Looks like it now fixed 2/4/2020 8:37am