Are you talking about duckduckgo? I tried `office -microsoft` just now and got the expected results: tv series, tv series podcast, government sites, bunch of businesses named Office. Nothing about Microsoft Office.
Yeah. For a site that claims to help people escape the filter bubble this seems like evidence that they don't. Maybe it's your location, or your typical searches that are giving you better results, but duckduckgo fails that test for me every time.
https://i.imgur.com/jrNw5LX.png
https://duckduckgo.com/?q=office+-microsoft&t=h_&ia=web