No flat earther believes earth is accelerating upwards. This is bogus claim. Earth is fixed and unmovable. Flat earth society is government controlled operation.
Pathetic try. Flat Earthers believe their world is accelerating upwards, being pushed by some unknown force, yet never hitting the speed of light.
In the Flat Earth model, 'gravity', rather than being a force, is the upward acceleration of the Earth. The Earth always accelerates upward at 1g, which is equivalent to the gravitational acceleration in the Round Earth model.https://www.theflatearthsociety.org/tiki/tiki-index.php?page=Gravity