An important point about this. If the file you copy from a source already has malware, where you store that malware will not remove that malware. Unless they have anti-malware software to check those uploads for you. Where you source them from is of the most importance. And checking them with your own local defenses before uploading or sharing them elsewhere is just as important.
I’m guessing Turbify might have failed on that note. What I will do is download them to a folder on my PC, then scan the images for malware. Any images with malware? POOF! — gone!
That's assuming the image has malware attached. The SSl may be out of date or some certification issue and somebody saw a "not secure" warning and freaked out.