Ask HN: Does Google try to throttle downloads of some apps?

I built a free app for a very niche community. (Target audience less than a million devices). Also I did not have any competition as such so here are the results. Day 1: 1500+ downloads Day 2: 2500+ downloads Day 3: 5000+ downloads Day 4: 1020 downloads day 5: 1018 downloads Day 6: 990 downloads Day 7: 1010 downloads This does not sound normal to me. Did my actually got unpopular or did play store did something ? For the keywords related to the community I am targetting the app continues to claim the top space and also a rating of 4.7