It really ought to be foalcon for non-humanoid underage, and loli/shota for anthro/humanized, as it’s always been.
The distinction has surely always been about the type of body, not strange discussions about whether or not anthro ponies classify as being closer to ponies or being closer to humans.
Replica is right here, err on the side of caution and if you think it could be considered that, please tag it as such. I think this is one of the few cases where you could argue “that’s over tagging” but I’m not going to complain here.
I’d rather people tag it as such, if they consider it. If it’s ponies, then it’s foalcon. If it’s decidedly moving away from pony, then tag it appropriately please.