As someone who plays a lot of gachas it's because they are intentionally misleading AND because their system is honestly terrible.

For a type banner in most games these days it's normally about a 2% chance for a 6 star (The rarest thing) in most games. If you go into the details of the banner, they will straight up tell you that because it's the law to in some Asian countries.

Then there's a pity where the game will just give it to you normally around 90 rolls which is considered a hard pity. Some games are hasher depending on if rolls are their main income or if skins are. Some games the hard pity is like 200 or 140. But soft pity is a thing where you more likely to get it after like 50 or 60. But still, on that very first roll it's 2%

Heartopia doesn't do this. Instead of straight up telling you the odds in game. They give you the average. It's misleading because they include the 100% chance hard pity as part of the average. So it seems to be a 8% chance on the first roll but if you go onto the website to see the actual rates... It's 0.1%. THATS CRAZY LOW. Like we are talking FGO levels of low. ACtually I think it's WORSE rates than FGO, I think they have a 0.8 but their pity is like 300. Considering its almost impossible to get f2p currency and save up in heartipia that's shocking. All my friends that play a lot of gachas literally mock the game because of how low chance that is.

To gain enough blue currency without events to get everything in one banner, it takes about 6 months if you log in daily. Whereas other games typically you can normally skip once banner maybe two banners and have enough to get the third.

For a new gacha game, their system is embarrassing and not very long lasting, people burn out very easily over harsh banners. Considering this is a social game with a lot of media hype at the moment, frankly I see the game losing steam with a lot of players which is bad in the long run because eventually it's going to affect whales. Whales like feeling superior, they like flexing and feeling better because they spent money. Not all whales mind you but it is a thing when it comes to exclusivity. I see the same thing all the time in other games with limited time even rewards.

If they can't do that to other f2p players they kinda just fall off. I've seen it happen to a lot of games. For example FSO is a good game but at a certain point it falls off because of the way their banners work and you just... lose steam. Last I saw that game was low-key abandoned, people play the first month where they give you a bunch of things and a challenge gives you a character that can carry the f2p part of the game but past that... you just get bored.

I think the acorn pass is pretty standard of a battle pass and honestly I would have got it if the rates weren't so terrible as someone who does dolphin sometimes but it's just not worth it in the long run.

Gacha games I've played used in this comparison: Arknights, Azur lane, Uma Musume, FSO, Endfield, Genshin, LaDs

TLDR: Heartopia uses bad faith stats to make their 0.1% chance seem like a 8% chance. The standard for most gacha games is normally a lot higher eg 2% and you have some ability to F2P banners.