Example:
https://duckduckgo.com/?t=ffab&q=imdb+game+of+thrones&ia=web
The example searches for "IMDB Game of Thrones" with the added "t=ffab" query parameter. This does not return IMDB in the search results.
If you remove "t=ffab" from the query parameters, IMDB appears at the top of the search results.
Answer there quotes a source that is deleted: "The t=mageia is intentionally added in the search configuration, as Mageia gets a tiny amount of money donated to it from duckduckgo for making it the default search engine in most of the browsers."
`ffab` sounds like "Firefox A/B", but that is pure speculation.
If you would like to remove that behavior, here is a suggestion: https://old.reddit.com/r/firefox/comments/cfo0xt/how_i_can_r...