I scraped the latest 1000 reviews (coincidentally almost exactly 12 months worth).
The "adware" reviews are all very recent with large amounts of votes.
They seem to start on December 18, with 162 1-star reviews in the following 25 days -- more than all the 1-star reviews in the 6 months prior.
I wouldn't be surprised if these reviews are not only automated spam, but are constantly being deleted and reposted to keep them "fresh", and at the top of the "relevant reviews".
The malware app was also called "barcode scanner", published by "the space team", so it wouldn't surprise me if a lot of people just found the more popular zxing app on the store and left reviews in the wrong place. I had the malware version installed and went through the same process Cedric did to find out that an update they pushed around that time turned on the bad behavior.
I scraped the latest 1000 reviews (coincidentally almost exactly 12 months worth).
The "adware" reviews are all very recent with large amounts of votes.
They seem to start on December 18, with 162 1-star reviews in the following 25 days -- more than all the 1-star reviews in the 6 months prior.
I wouldn't be surprised if these reviews are not only automated spam, but are constantly being deleted and reposted to keep them "fresh", and at the top of the "relevant reviews".
Charts: https://imgur.com/a/QUyHcHu
CSV of review data: https://pastebin.com/ZanYgd5Y