FEW under the FAQ page shows a diagram of the Sun moving in a circle centred on the north pole. The radius of the circle varies with the seasons through the year.
It is easy to draw a simple diagram and write a statement to the effect of
When the sun is further away from the North Pole, it's winter in the northern hemiplane (or hemisphere) and summer in the south. A more simplistic picture can be found below.
Anyone could have drawn a diagram and attached a label to it. Not hard to do. Now explain to me how this actually works in the real world. We have our observation, now lets identify a cause for what we see. What is the mechanism that makes the Sun go around the NP and vary its distance from the NP. Angular momentum (or circular motion if you prefer) needs to have a force driving it so what is the force or forces in this case? FE hypothesis doesn't accept the existence of gravity and even if it did I cannot see a source of any such gravitational force (a mass of some kind) in this case. There would need to be a very large mass (much more massive than the Sun itself) located over the NP and I cannot find any evidence for the existence of any such mass.
For Flat Earthers to be sure that this is true they must know what mechanism this is otherwise this sort of motion cannot be proved and is therefore unfounded.