While I like the general idea of Ecosia (in that it's a less harmful ad-funded service) they do share user IP addresses with their search partners (Google and Microsoft).

> We, and our search partners, collect your IP address in order to protect our service against spammers trying to conduct fraud or to up-rank specific search results.

Src.: https://www.ecosia.org/privacy

This shouldn't necessarily stop anyone; I think it should just be mentioned when it is suggested as an alternative to DuckDuckGo. You probably wouldn't switch from a search engine that proxies all favicons to avoid tracking to one that sells your identity to Google and Microsoft for tree-money.