In Settings/Details/Legal Notice, there is an explanation of how search results are (or are not) shared with specific third parties. There is a link to a page that lists those third parties:
https://www.ubuntu.com/privacy-policy/third-parties
However the link is broken. Is there a valid link somewhere?
The link has been moved a bit. For starters, check https://www.ubuntu.com/privacy-policy/:
That last sentence is a link to the updated list. The software just hasn't been updated in accordance (which would probably require a complicated SRU).
For completeness, the link lists, at the moment: