I am always surprised when (be it greenwashing or not) companies call themselves "search engine" when in fact ... they actually aren't a search "engine".

They don't have any indexing/searching technology, they just re-use another search technology in white-label.

We can criticize Google for many things, but at least those guys really built a technology, from scratch.

TL;DR: Calling Ecosia a search engine is like calling yourself a "restaurant" when all you're actually doing is reheating factory-prepared meals.