Why are cursed harem protag tropes so cute when it’s yuri? Truly a mystery of the world and definitely not the result of bias.
Probably because most harem protag tropes are ways to speedrun romantic attraction and sex without what most people would consider an 'appropriate' or 'believable' investment in terms of time and effort. So you have women randomly flashing guys and falling tit-first onto their faces through contrived coincidences instead of a mutually agreed-upon decision to engage in intercourse. This is hilariously ironic, because the intent is to make a sexually-charged encounter between a ridiculously cute girl and an average guy seem 'realistic', but the circumstances that lead into it are the pinnacle of pandering bullshit. Most people understand what authors are trying to do here, because harems aren't the most subtle of genres, and feel uncomfortable because of the gender dynamics at play- most romances tend to portray women as passive in terms of initiating romance while men generally make the first move and are later given consent.
By removing this process and the man's agency via 'lucky pervert' moments, the titillation feels 'unearned' and 'cheap', while the woman's evident discomfiture at being pushed into a compromising situation is also quite disturbing. When both parties involved are women, however, the gender dynamic largely vanishes, and the knee-jerk 'ugh' that a lot of people feel while seeing harem tropes is removed, leaving only amusement at the suddenness of the situation and excitement at the sight of an encounter. In short, stuff that would never be condoned or appreciated between a man and a woman is often forgiven or actively idealized when women are involved. So a scene where a man kisses a woman out of the blue to express attraction might make us cringe, but if it's done between two women, then the novelty of the interaction and the relative lack of media-conditioned mores would blunt the stigma. Sometimes, this is justifiable, because lesbians need their wish-fulfilment and rep after centuries of being excluded from media, and sometimes, it isn't- a lot of people will defend rape or molestation when it's girl on girl. As with everything, context is king.
