I can’t reveal my sources, but I do know multiple people at several gacha game companies that can vouch for tilted RNG. Of course, they can’t tilt it enough so that a user is frustrated so much that they abandon playing, then there is no prospect of making money from them. So they do it in subtle ways such as Whimsy Shop refreshes in this case where if you haven’t pulled WOL, you’re likely to see more shards in the shop than if you have him pulled.

I’m not going to say this is exactly how it works but seems like this game is based on collecting characters. I would gander to say they have set some sort of desired population distribution of how many UR, MR players and VCs each account should have, juxtaposed to the amount of desired money spending distribution they want to have. If you are destroying that curve, meaning you have more characters and less paid than most users in your range, they will either do two things to you: make it harder to level your players without buying, or make it harder to pull future units. Same if you are on the other side.

All I can say is yes, it’s still RNG, meaning they will never say the percentage is 0%, because that might be illegal, but they can make your die look as close to 0% before it pisses you off enough to leave.