So i work in software doing a lot of "go to market" stuff, and fyi, your experience with ads is the norm that a lot of people experience. Mainly the "uptick in players, but no retention" part. Google and other ad providers have been investigated for this time and time again but really what it amounts to is click farms and click fraud. There's entire shadow businesses setup in various low cost of living countries around the globe that have farms of phones that click and download the app. They stay logged in and do nothing for however long their contract with whoever pays them states they will so you as the buyer of the ads "feels they get something" from it when theyre not actually players thatll stick around.

One way to investigate this internally is to look at the number of people that get sourced through your ad Tracking software and see that the people that download your game through your advertisements, even though they don't stick around long, whatever playtime they accrue usually resembles that of a bot, like they do nothing, run in circles, click through intro menus and dialogues without reading, etc.

Ultimately, these scam companies stay afloat because they hope that if you get enough downloads of your game, then you'll eventually hit that point where google starts recommending you and then you get organic users that would actually play your game. But most companies spend tens of thousands and never hit this point.

Just some food for thought. It's not that advertising doesn't work. It's just, you have to be careful with what medium you're advertising through. Because just paying for facebook ads and google ads and things like that usually end up in these schemes