I have yet to see a flat earth explanation of the horizon.
I'm not an expert by any means on flat earth, but this is the way it seems to me.:
If the earth was flat, there would be no curvature of the earth.
If there was no curvature of the earth, there would be no horizon.
If there was no horizon there would be no limit to the distance you would be able to see.
If there was no limit to the distance you could see, and if you were high enough above the mountains, buildings or other objects, and with a telescope of high enough power, you should be able to see the ice wall from any place on a flat earth.
But the thickness of the "atmoplane" , haze, and other effects, would prevent you from seeing the ice wall.
Therefore, you would not see a horizon, but (Quote I have seen from the flat earth) "You would see an indistinct blur, which fades away at an indefinite distance."
Correct me, flat earthers, if you have a better explanation .