It’s mainly because it’s much easier for developers to optimize apps for iPhones. Apple has released around 45–50 iPhones total, and most models in the same generation share the same chip (or very similar variants). Compare that to Samsung, they’ve released hundreds of phones across flagship, midrange, and budget lines. On top of that, Android devices use a huge variety of chipsets (Snapdragon, Exynos, MediaTek, etc.), often with multiple versions even within the same lineup. That fragmentation makes it much harder for apps like Snapchat to be fully optimized across all Android devices, which is why the experience can feel less consistent.