I have noted the exact same thing happening. I had a Fall Guys game series I was working on, and went through about 20 duplicates in order to finally get a look and feel that was how I wanted to have the franchise look like. The reasons for duplicates in this case is because we might start with a grand idea, but then the map design becomes to big, and we downscale everytime until we get to a design that is more practical and managemable in terms of Memory. Then I set about desigining game 1, published it and it rarely went into discovery. It also took like 5 days before it did.
Then I duplicated the game 1 content via Migration method, because had another idea for a game world, and not to start from scratch to setup all the devices again, and I created a new game world environment.
But since publishing this 2nd game, its been horrendous to get it into Discovery. I waited almost 5 days before it was first time in discovery, and it was only in NEw & Update for about 2 hours before dissapearing again. Then again waited many days before it showed up finally in Discover again, just to quickly dissapear again.
Both these games where brand new, and the only this is that to ensure a productive workflow, we as creators will duplicate projects several times. Especially if you are making a game series with 4 to 6 games in the series.
But now its become clear that these maps almost get no time in Discovery.
The only time I managed to “force” the new games in to discovery was when I made several updates later on, and it went in to NEw & Update. But the usual about 2 weeks that you get in dicovery for brand new maps was completely absent for these 2 games when I just launched them.
Compare this to our TMNT game which we published, and it stayed for almost 2 weeks in Discover New & Updated and it greatly helped to improve the game. The TMNT was a brand new island created, and was never duplicated.
So after publishign about 4 games by now, I have seen that when an island is published that has been '“duplicate” but it actually contains a brand new design, you are just keeping your mechanics to save time, then it happens that your game struggles in Discovery although its a brand new game.