Ewww! That is legit bestiality/Zoophilia in my opinion. A feral adult horse getting sucked by another adult feral horse with consent is not bestiality/zoophilia to me, It's legit more a fictional mating fantasy, especially if you are fantasize about yourself "being" the horse, which is far different to me from a human "sexually abusing a horse".
Feral Discourse by the younger and newer furries has been extremely ridiculous these days to me, especially since this was considered acceptable before the 2020s and that many prude non-furries would argue that furry porn or yiff promotes bestality/zoophilia in general regardless of if they are mating on two legs or four legs or what type of genitals they have.
Also, fuck the Loli/Shota/Cub comparison they say! That is nothing like having sex with a child or having sex with a thousand year old child. That is legit pedophilia to me when feral on feral is legit adult characters of adult ages and maturity mating with each other like on the Discovery Channel.
One furry I like creeps me out with the human on feral art, but will only cancel that artist if they have been confirmed to be a zoophile in real life and the human on feral bear has mildly got a pass for me slightly due to "Baldur's Gate 3" as long as it's not in real life and you are not sexually atracted to real bears in real life. Bear anatomy also gets kind of tricky due to standing on two legs since Baloo technically counts as feral if naked in Jungle Book but anthro if wearing clothes and flying an airplane in Tailspin.
Also, Harkness Test! Not technically legal advice from a lawyer on obscenity but still good on the subject of sexual consent between humans and creatures or creatures on creatures. Harkness Test says since many dragons in pop culture are very intelligent and can talk, It's okay for an adult human or humanoid to have sex with a dragon as long as they can both sexually consent.