I think a case could be made that Nat Geo certainly took a hit to their reputation:
"The manipulation damaged the magazine’s credibility. Tom Kennedy, who became National Geographic’s Director of Photography after the incident, stated: “We no longer use that technology to manipulate elements in a photo simply to achieve a more compelling graphic effect. We regarded that afterwards as a mistake, and we wouldn’t repeat that mistake today.”
In any case, I was certain it had happened but this isn't exactly compelling evidence that it's a widespread problem. A much more recent example would help your case. Also, (as you mentioned) this is a case of an outlet fooling people with their own fakes, not an outlet getting fooled by a fake which is more what I was referring to.
"The manipulation damaged the magazine’s credibility. Tom Kennedy, who became National Geographic’s Director of Photography after the incident, stated: “We no longer use that technology to manipulate elements in a photo simply to achieve a more compelling graphic effect. We regarded that afterwards as a mistake, and we wouldn’t repeat that mistake today.”
[https://www.alteredimagesbdc.org/national-geographic/]
In any case, I was certain it had happened but this isn't exactly compelling evidence that it's a widespread problem. A much more recent example would help your case. Also, (as you mentioned) this is a case of an outlet fooling people with their own fakes, not an outlet getting fooled by a fake which is more what I was referring to.