qwant main founder is a shady microsoft zealot and was in trouble for weird stuff (dunno how it did turn out). AFAIK, qwant is running ads from the advertisment company of microsoft like duckduckgo. It is said qwant mostly use bing as its backend (they have small indexing engine/web crawler on their own though, but not main).

Usually, when something online is "free", follow the _real_ money: which advertisment company is making money out of it? is user data sold to brokers? is there a fund behind it financing (vanguard/blackrock/etc)?