12-08-2019, 08:43 PM
Yes, some of the coffee color is in that brown area and a fuzzy select with a threshold of 90 selects it. Not called fuzzy for nothing 
A Gimp 2.10 tip see: https://i.imgur.com/qKurxgZ.jpg
1. Bottom of the fuzzy select is a tick box labeled 'Draw Mask' That overlays the selection with a magenta mask, you see that the brown area is also affected.
2. Still in the fuzzy select tool, you can click and drag to adjust the threshold and the change is shown in the mask. You actually need a threshold round the 50 mark.
3. Let go the mouse, the adjusted selection remains and cuts as shown.
A Gimp 2.10 tip see: https://i.imgur.com/qKurxgZ.jpg
1. Bottom of the fuzzy select is a tick box labeled 'Draw Mask' That overlays the selection with a magenta mask, you see that the brown area is also affected.
2. Still in the fuzzy select tool, you can click and drag to adjust the threshold and the change is shown in the mask. You actually need a threshold round the 50 mark.
3. Let go the mouse, the adjusted selection remains and cuts as shown.