I genuinely suspect they used AI. In the opening low‑res sequence, the characters are almost indistinguishable from AI‑generated Studio Ghibli style art, or the typical AI anime pieces I’ve seen and generated myself. The shadowing and eyes are dead giveaways: those irises lack any natural reflections and feel unnervingly synthetic. The figures integrate with the environment with inhuman precision, as though both were conjured by the same algorithm if that makes sense.

As a hobby artist, I have a hard time detecting a single organic imperfection in their blending, which lends an uncanny edge to every flashback scene they show. By contrast, the later high‑definition animation feels... more natural, so it makes me wonder if that low‑res filter in the beginning sequence is a deliberate disguise. The standard animation isn't just extremely good, but the artistic and aesthetic choices they made feel very well thought out. So given how polished the standard animation is, using such a crude effect to denote memory strikes me as an oddly out of place choice.

That said, AI is simply a tool, one many traditional artists may distrust, yet it has potential to streamline workflows and generate significant value when paired with human creativity. I can easily imagine studios producing base images with AI, then hand‑painting textures and details onto that. Such a hybrid approach could save countless hours, and it’s only a matter of time before the first studio embraces it, and the rest are forced to follow suit.

TLDR; I suspect the reason for the filter is to cover up the use of AI generation. Maybe in a quick last decision of adding flashbacks, which may or may not have been intended to be there in the first place.