According to Gray, Google had run a program to mess with the "#SemanticMatching" on queries, silently appending terms to users' searches that caused them to return more ads - and worse results. This generated more revenue for Google, at the expense of advertisers who got billed to serve ads that didn't even match user queries.
Google forcefully disputed this claim:
https://twitter.com/searchliaison/status/1709726778170786297
13/
An opinion piece recently appeared stating that Google “just flat out deletes queries and replaces them with ones that monetize better.” We don’t. The piece contains serious inaccuracies about how Google Search works. The organic (IE: non-sponsored) results you see in Search are…
They manipulated the "#SemanticMatching" on user queries:
https://www.wired.com/story/google-antitrust-lawsuit-search-results/
When you send a query to Google, it expands that query with terms that are similar - for example, if you search on "Weds" it might also search for "Wednesday." In the slides shown in the Google trial, we learned about another kind of semantic matching that Google performed, this one intended to turn your search results into "a twisted shopping mall you can’t escape."
30/
Cory Doctorow