The ChimeraX  panels are can be dragged and dropped on the main ChimeraX window to allow stacking them.  In your case you dragged the AlphaFold Run panel on top of the Log panel.  Then it shows the two tabs (AlphaFold Run, Log) at the bottom and you can click on those to switch between them.  You can make the AlphaFold Run window free-floating again by showing its tab then dragging the title-bar of the panel out of the main ChimeraX window.  All the ChimeraX panels work this way -- they can be made free-floating windows or "docked" in the main window.

  Sometimes it is annoying when you drag a ChimeraX window and it tries to drop it on top of another panel.  You can tell ChimeraX to not allow dropping the AlphaFold Run window on another panel using the command

ui dockable false "AlphaFold Run"

  Tom