You've already pointed it out the reason. It's cause the story contains r@pe... and while some other stories which glorifies it, the high ratings might've been because at first they thought it was good and forgot to change their ratings as the story unfolds the toxic side. And yes, this story did write the SA and r@pe as it is and the psychological pain but we'll see in the end of the story cause spoiler alert; heard the uke ends up with the seme. And I guess some readers here in this site are tired of seeing the same shitty story that they probably dropped this, and if they ever rated other toxic one high, I can only assure you they probably stick around because of the art.
But honestly, it depends on how the author/story tries to paint and tell a story with depiction of abuse and SA... for me, as I've read a lot of toxic stories and some are really disturbing as fck, the only thing I can say is; it's too much but I stick around cause I wanna know what the mc will do next. I wanna see some revenge arc, ngl.

So far I don’t understand the low rating. Yes it’s a darker theme but objectively it’s written well. The author actually depicts rape as rape and psychological pain as real pain with real effects. Maybe written well is a stretch but it’s definitely written better than a lot of these shallow rape filled BLs they glorify it to the point readers don’t even realize or acknowledge the severity of it and those are rated highly. No hate but I wanna know why it’s rated so low. I’ve seen straight porn doujins with sexualised rape higher than this.