If we were to observe the direction to the Sun over the entire course of the day, on multiple locations on Earth’s surface, and then plot the results on the so-called flat-Earth map; then they would not consistently point to the position of the Sun that is calculated from its location on such map.
This fact happens because the flat-Earth map is not the correct description of the real Earth.
These discrepancies are evident in sunrises and sunsets. The observed directions to the sun almost never point to the correct location of the Sun on the flat-Earth model.
Around solstices, we can see extreme cases of such discrepancies: the directions to the Sun, at some point, would point to the opposite from the location of the Sun according to such map.
The flat-Earth model fails to describe simple facts we encounter every day, like the position of the Sun. On the other hand, the globe model of the Earth is 100% consistent with observation.