^^There was a pretty mediocre lesbian porno with a super tall woman and very short woman and this is one of the scenes. That scene was better than the whole porno which was basically just straight guy lesbian sex. But the scene has imprinted itself in collective consciousness because what it promised was so strong.
TBH given how long she's been a fixture of Liyue governement Ganyu's any tendencies would be pretty much public knowledge - and certainly the sorts of mortals who make it into a body like the Qixing in the first place will have snooped out such details long ago...