[Q] Unityadscache folder and hidden ads topic

I'm going to try not to sound like a conspiracy theorist, but I'm genuinely wondering if a game dev is trying to be sneaky with ads by hiding them from users but still getting paid from them.

I recently started playing an android game that runs on an in-game currency system. You pay real money for some fake money that can be used in the game. There are no other advertisements in the game. Recently I've noticed a "unityadscache" folder that will have one or two, 1 to 2 Mb videos in it. I can delete them and the folder but it keeps reappearing. So I spent some time verifying that this folder and these videos kept showing up when this game was started. It happens every time. I've searched around and this folder seems to get attributed to a few other games. Oh, and this folder has a .nomedia file in it so the ads don't get seen by gallery apps.

My question is, are these devs trying to somehow get ad views by surreptitiously loading these video ads in the background? That seems sneaky on a whole bunch of levels. I would assume that if that's the case it would be frowned on by most users if they knew about it. I'm all for devs getting paid for free apps by using ads, but I'd prefer they were up front about it. Also of note is that this game will not run with adblock plus running, which seems odd for a game without ads, right?

I contacted unity about this and they didn't think it was that odd, that possibly they used to have unityads at some point but removed them and left the code behind. Here's the thing though- I got this game on day one release. There's never been any ads. Plus, it's an ad company I trust them about a foot less than I could throw them. I could contact the game devs but I'm saving that until I know what I'm dealing with.

So, am I nuts?