I drew up an illustration to help explain.
The left side depicts how sun light at a low angle through an atmosphere (convex) will bend light to follow the curve of the earth. It does so in a sleight amount, resulting in a sun that appears slightly higher than its geometric position, by a distance about the same angular width of the sun or about half a degree. Without an atmosphere, the sun would set about a minute earlier.
Th right side depicts how sun light would bend due to upward electromagnetic acceleration. The theory describes light path that bends in the opposite direction of globe earth's refraction, causing the sun to appear lower than it's actual position. This would amount to 17-20 or more degrees, depending on the dimensions of the earth, sun and the distance of sun over the earth.
On a globe earth, the downward-refracted light would cause vertical distortion that would "squash" the appearance of the sun since the lower portion of the sun is being more heavily refracted than the upper portion of the sun.
On a flat earth with EA, the upward-bending light would cause a vertical distortion that would elongate the appearance of the sun since the portion of the sun further away is more heavily affected by EA than the portion closer to the observer. (With EA, the observer is actually seeing the side of the sun that is facing earth, with its light bent toward the horizontal such that the sun is turned nearly 90° when seen low on the horizon).
Does the sun at sunset appear squashed or elongated?