that "Google made their search results worse on purpose to get more ad impressions" article that's going around is based on an internal email chain from a legal filing, in which an employee mentions this potential approach for increasing engagement metrics... as an example of a bad approach and not something they'd be comfortable doing.
based on my reading, there's nothing in here that says they actually did it. I can't see anything in there that supports that claim.
the article links to the results of a survey on people's perception on the quality of Google results over time, showing a negative trend, and I think that's something we all share similar anecdotal feelings about. but then it goes on to make the direct claim that they did it on purpose, which is (as far as I can tell) a claim without any concrete basis.