'The flat model explains the seasons'

"The seasons are explained by the Sun's distance - it is closer in summer and farther in winter."

If the Sun were closer in summer, its apparent size would be larger in summer. It is not: pinhole measurements at sunrise, at sunset and at noon always give about 0.53°. The Sun's noon altitude instead varies with the seasons in exactly the way the 23.4° axial tilt predicts: altitude = 90° − latitude ∓ 23.44°. On the 2019 December solstice, a shadow measurement at about 44° N gave 22.54° - matching the globe prediction (22.56°) to within 0.02°, and about 60× the altitude the flat model's own geometry gives for that latitude on the solstice.

The constant 0.53° Sun (pinhole camera, any time of day); the 2019 December solstice measurement (22.54° at ~44° N, matching 90° − 44° − 23.44°); the 24-hour Sun at ~79° S in December (TFE 2024) - all three are the same 23.4° tilt, measured three different ways.