They’re like dogs that were bred wrong :(
“Moe breathing?” The constant snuffling and yelping you mistake for “KYAAA~’s” and “nyas” and “chu’s” is because anime girl shops keep selectively breeding for smaller and smaller nasal passages, as is the case with pugs - same for the large eyes! Anime girl eyes have gotten so excessively large and shallow in the skull they can pop out if they sneeze or even just tumble :(
Speaking of tumbling, their progressively weakened collagens due to the malpractice of curators has caused arthritis and improperly formed musculature, leading to a lack of independence, limping, and eventual mobility failure - as can be seen in the top gif. Not dissimilar to the mistreatment of Scottish fold cats.
You might also see the anime girl in the top gif who has had her growth stunted. You can see her movements are lethargic and clumsy. This is also how people keep ‘micro pigs’ small. Please remember that there is no such thing as ‘ethical lolis.’ If your anime girl is that small and underdeveloped at adulthood, then there is something wrong with her, and you should take her to the vet immediately.
As for the bottom gif, that one has likely been inbred to get the desired cel shading look that has been popularized by modern anime girl show standards, and will need assistance eating, drinking, and cleaning herself her entire life. It’s really tragic, and no way for a creature to live. We need to push for a better regulated anime girl market.