What i came to know from other community about this issue is
“You should not store Facebook CDN URLs for long time use – they can change over time.
Either request the actual image and copy that to your server – or request the current CDN URL regularly.
(You might be tempted to try other workarounds, like extracting the actual image source URL from the CDN link, but I would advise against that – because the format of that might change at any time as well.)”