Person wanted a certain character they suggested to look morbidly obese. Mofu-san put it to a poll to let everyone have a chance at what they want the character to look like and everyone voted for to be thick but not morbidly obese (you can see this character and poll on Mofu's Subscribestar page). This angered them and now they've been harassing Mofu-san for most of this year, including false reports and constantly spamming Mofu's comment section on their PixivFanbox page.