One of my apps showed a sudden, massive decrease in Play Store user acquisition early October. I didn't update the app around that time nor did I change anything in the store listing. The attached chart shows the user acquisitions over the last 180 days. As you can see, the user growth was fairly stable and growing before the drop.
I've searched the sub for similar issues, but there's a factor that may have affected the decrease in my case: the drop occurred almost immediately after a Google Ads app install ad campaign ended I was running (you can see the increase


