"Funding This study has been supported by Tchibo GmbH, Hamburg, Germany." Tchibo is a German chain of coffee retailers and cafés known for its range of non-coffee products that change weekly. https://en.wikipedia.org/wiki/Tchibo Number of locations 700 shops (Germany) 300 (rest of world) They might want to make some in-store claims about Dark Roast...
I'm generally sceptical of all studies about coffee for this very reason. There's a lot of bullshit studies around food and supplements funded with people with strongly vested interests in selling more product. It's a real problem. For any given supplement, you can often find multiple studies supporting its use and multiple studies saying it's harmful. When it comes to coffee specifically, if you listen to the studie…
We still aren't even sure what general diet is fully optimal long term let alone if one constituent can give actual life expectancy benefits.