Hi Reinier,
You have absolutely nothing to worry about

The Genus Grammostola (which includes the Chilean Rose and the Chaco Golden Knee) is known (and easily identified) by the so called "mirror patch" on the abdomen, these are not scabs.
It is true that the Chilean rose (and the Chaco Golden Knee) can go without food for months and this is considered normal behaviour for them. Keep offering food once a week and if not eaten, remember to remove the food after about 24 hours.
From the picture, your T looks perfectly healthy and plump so you can stop worrying
Also looks like you have a Red Colour Phase G. rosea there