TLDR - NO, Flat Earthers do not believe this shit. 

Across the internet on the various platforms, there are posts and discourse pertaining to "Clouds Behind the Sun"

They are trying to make it appear that "Flat-Earthers" stupidly believe that the Sun is so close to Earth that its in the clouds and airplanes are liable to fly into it.  

Do you think the sun is also in front of these power lines?

No, its called Bleeding when the camera sensor is overwhelmed by too much light - exactly the same as in the thinner portions of the clouds.

Relating this Misinformation to Flat Earth is part of a False Flag Operation.  

 A false flag operation is an act committed with the intent of disguising the actual source of responsibility and pinning blame on another party.  

This is obviously an effect of overexposure.   

Recently, people have been sharing imagery depicting the sun or the moon appearing to be in front of clouds. This imagery, while visually appealing, is misleading, disingenuous, and wrong. To understand why, let’s explore the physics behind this phenomenon.

When viewed from Earth, the sun and the moon appear to move along a path in the sky known as the ecliptic. Clouds, on the other hand, tend to remain stationary in the sky. This means that when the sun or moon moves beneath a cloud, the effect of the sun or moon appearing to be in front of the cloud is an optical illusion caused by perspective; the sun or moon is actually behind the cloud. It should also be noted that this phenomenon is more common near sunrise and sunset, when the sun or moon appears to be close to the horizon.

The danger of sharing this misleading imagery is that it could be perceived as factual, leading some to believe things that may not be true. This isn’t just a minor issue; it could have serious implications in fields like astrology, astronomy, and meteorology, where accurate information is critical to making sound decisions.

In conclusion, while imagery of the sun or moon appearing to be in front of clouds can be visually striking, the reality is that it is, in fact, an optical illusion. If you encounter this kind of imagery, it’s important to remember that it is misleading, disingenuous, and wrong, and should not be spread without acknowledging the physics behind it.