In photography, bokeh is the way a camera lens renders out-of-focus points of lights. The shape of bokeh depends on the camera lens more than the out-of-focus objects themselves.

Some flat-Earthers do not know how to take correctly focused pictures of distant planets and stars due to their lack of knowledge and the unsuitability of their camera for the purpose. All they are getting are bokeh, which does not tell us much about the intended objects.

A different camera lens can produce a different shape of bokeh. Concentric circles (or onion ring, or shooting target) are usually caused by aspherical lens elements. Polygonal shapes are from the shapes of the aperture of the lens when stopped down. Rippling motions in a video are the result of atmospheric turbulence. Donut shaped bokeh is due to the obstruction by the secondary mirror in a mirror lens. The shape of bokeh tells us more about the camera and lens than the intended objects.

Flat-Earthers invented various assumptions and even devised wild conspiracy theories to explain why stars and planets do not appear the way they are supposed to be. However, the real explanation is much simpler: the shapes are bokeh and tells us more about their photography skills (or lack thereof) more than about the intended objects.