Bug overview description.
As seen here and here, the site force adds non working and non removable urls into source fields based on direct image links.
here it adds "lei_feiyang.deviantart.com" and here it adds "inar_of_shilmista.deviantart.com"

What part(s) of the site page(s) are affected?
All post pages.

What is the expected behavior?
That only relevant links appear in source field. Not Broken ones.

What actual behavior is given instead?
There should not be non-working irrelevant links that cannot be removed.

Can you reproduce the bug every time?
yes