Some flat-Earthers discovered images of multiple suns in the sky. They jumped to the conclusion that it proves whatever they want it to confirm. In reality, we can explain them without going for farfetched scenarios.
Photoshop trolling is prevalent in flat-Earth communities. The most common form involves finding a suitable landscape photo and using Photoshop or a similar app to turn it reddish as though it was taken on Mars. Then, the result is placed next to the original with a caption added to imply that the “Mars photo” was from NASA, and they faked it from the original.
Flat-Earthers will not bother confirming if the image was really from NASA. They cannot realize that they are being trolled —many memes containing such images spread in flat Earth communities as hoaxes.
The horizon appears flat because the curvature is too small when observed from near the Earth’s surface. However, in some cases, we can exaggerate the curve by taking photographs of the horizon and then magnifying the results vertically.
Magnifying in such a way will also magnify the distortions introduced by the camera lens. We will need to control these distortions using proper photography techniques, or by placing a known straight object as a control object in the frame, close to the horizon. If successful, then the remaining curvature in the photograph can only come from the curvature of the Earth.