Jody‘s crew came across some disturbing articles that tell about fillers being added to coffee. You might be better off buying your coffee as beans and grinding them yourself.
According to one article from Time, they have been using fillers like wheat, soybean, brown sugar, barley, corn, seeds, sticks, and twigs in coffee. This is due to the recent coffee shortages due to climate changes.
Brazil especially has been experiencing a terrible drought and rust fungus to this crop.
According to Quartz, coffee is one of the most frequently adulterated foods.
You won’t be able to see the counterfeit materials in ground coffee. It can be tested with chromatography but who has that? About 76% of the world’s coffee is both roast and ground so they will not know whether or not their coffee has fillers.