Bottoming from the top is a phenomenon that happens during BDSM scenes, during which the top is actually relying on the bottom to tell them what to do. Although the top is supposedly in the "dominant" role during the scene, they are acting from a bottom perspective, leaving the bottom to have to take on the topping role.
More About Bottoming From the Top
Bottoming from the top--and its opposite, topping from the bottom---happens most often when limits, boundaries, and expectations are not set properly before a scene. When a top is acting like a bottom, the bottom is left having to take control.
However, such scenes are usually unsatisfying for both partners. The bottom is frustrated because they couldn't just feel and enjoy the scene, and the top is frustrated because they didn't give the bottom what they wanted.
Most often, bottoming from the top happens when the top is usually a bottom, or when the top is unsure or unclear on the purpose of the scene and what is expected of them. This is why plenty of negotiation is necessary before beginning a scene.