As an old person who plays Genshin Impact, the “character banners” are 100% loot boxes. They have a pity system which guarantees a five star character after 100 “wishes” but even then it may not be the character you wanted. You might have to “wish” up to 200 times to get the five star character you are “wishing” for on the banner. Since you are not buying the character out right and gambling to get them it’s a loot box.
For anyone who doesn’t play “character banners” are a limited run (3 weeks) of a five star character that you can only get from the banner. “Wishes” are like rolls for the character. Each wish you lose gives you either a weapon (3 star/practically useless in game) and every 10 wishes gurantees a four star weapon or four star character.
So I think the “horse is likely to bite you if you’re looking in its mouth too closely” is an assumption we both had about this phrase. I grew up in the suburbs and rarely saw horses so I assumed this phrase was about it possibly bitting. However I now live in a more rural area and horses are pretty sweet and the only reason anyone looks in their mouth is to make sure they’re healthy or figure their age. I’m guessing you, like me, also grew up not around horses so we assumed the English version means something different than it probably did in the past when horses were common place.