Here's where right clicking on the image in Google Photos can go wrong. You end up getting a link from google's CDN's which doesn't always work (depending on which region the viewer is in), and those links will (and frequently) expire as google flushes their CDN.
Here is what I see:
And I get two of those greyed "stop signs".
Looking at the URL of the photos I see this URL:
But it looks like because you right-clicked the photo in Google Photos and did the open image in new tab trick and grabbed the URL, which is the photo in Googles CDN's.