Devil's advocacy time:

the bottom one is emulated, the PS2 only went as high as ~496p and you absolutely cannot get clarity like that below 1080p.

The resolution also varied by game. Some games, such as DMC3, had poor quality assets but ran at 480p/60fps. Other games, such as MGS3, had very high quality assets but ran at as low 240~360p and below 20fps.

Monster hunter was the latter. It is a blurry mess on the original hardware with a sluggish unstable framerate---but it emulates very well at modern resolutions/framerates since you get to see the assets in their full detail (while fps/resolution centric games like DMC3 emulate poorly since their assets' flaws are on full display)

MH also only uses very tiny playable areas, which also allows them to maximize the quality of their foreground assets since they don't need to render many distant assets.

It also allows them to carefully curate the player's perspectives, which enables a lot of visual trickery to save FPS&memory. For example, the gameworld in the picture above ends at the mountains on either side of the river. The green hills beyond that are part of the 2d skybox.

Here is the location in question as rendered by an actual PS2.

Also, Pokemon Arceus's distant terrain and lighting honestly doesn't look much worse than the average for most switch games I've seen w/ a similar scope and art style, such as Hyrule Warrior's Age of Calamity's intersecting-flat-texture trees

Which, for the sake of trivia, is a very resource-efficient way of rendering trees and grass/bushes that was used by a metric fuckton of resource-intensive games up until the mid-late 2000s. Even WoW used it as recently as Wrath of the Lich King in 2008, before dropping it in 2011's Cataclysm. It did see some use into the 2010s, though, especially in open world sandbox games like Minecraft, 7 days to die, and such which used it for grass/brush.