They use Googles results with a bit of Bing mixed in. Bangs should work too, like !wiki for Wikipedia or !d for DeepL They’re partly owned by an adtech company though (and say they dont share anything).

about 32ct/kWh including all costs (Germany)

They are using MBFC’s bias rating too, with some additional ratings from other sources for a few publishers. Seems to have a strong US-centric view as well.