The plot may be similar while the character's personality or character's development is totally different and the vibe of the whole story is different as a result.
For example, "Payback" has the same arrogant and rough sponsor seme who treats uke without any respect, but uke in the story has such a wholesome strong, resistant and self aware personality that the vibe of the whole story is good, although seme is a dick till the end.
One more example, "Waterside night". Another dickhead seme who rapes uke at the first sight and manipulates him till the uke is almost mentally broken, but the retribution part in this story is so damn good!! I really felt how deeply remorseful seme is, the thought process of seme and the art made me believe that this dickhead for really real is in love sincerely. So yeah he got my blessings to be with uke despite being an asshole.
So I think the reason the comments on this webtoon is mostly negative is not because of the first comment's negative vibe, but because the characters are poorly written and their relationship has no development, just ungrounded switch that makes uke fall for someone who disrespects and degrades him on daily bases and seme suddenly treat uke kindly despite treating him as a trash during the whole story. It is also frustrating that there is no retribution for seme in the second season, he is forgiven without any efforts

Someone needs to do a study on how polar opposite comment sections are on stories that are very similar. I've read variations of this plot more times than I can count, if it's not reincarnation, it's some bitter ML meeting his childhood friend MC again as they are older and it's basically the same plot with different fonts.....yet the comments are 80% positive and sweeping the glaring rape and abuse under the rug. Then, every now and then, you get a comment section like this which as of March 5th 2025 is almost completely negative. Is it a matter of "the vibe" of the first comments carrying on so negativety breeds more negativety in the comment or is there actually something very small that is different between the stories which triggers readers....so weird