Genetically is there a reason some shinies are less conspicuous than others? A shiny eevee has less ability to hide from predators due to silver coloring but a Pokémon like gabite does not change much when altered forms are involved. Moreover is the reason shinies are so rare due to their lack of ability to hide or hunt due to their coloring make them more of a target? I gave a hiding example with eevee but for hunting a shiny sharpedo is more likely to be spotted by prey, giving warning by hue

Actually, the reason why shinies are rarer than standard pokémon is because shininess is a genetic mutation. It’s very much the same as albinism in humans. Just as albinism is possible but extremely rare in humans (and is often tied to health problems and is, thus, not an ideal condition), shininess is likewise possible, rare, and may lead to issues for the individual. (In some cases, those issues may even be the same—that is, the issues may actually be tied to health problems in certain pokémon species, not simply conspicuousness.)

Granted, yes, in some cases, shiny populations of some species are low because the conspicuousness of a shiny-variant pokémon makes it difficult for individuals to hunt or hide from predators, but really, it’s just that shiny populations are low to begin with purely because shininess is a mutation.