I think this is a good example of what people mean when they have complaints with the use of rape as a bl trope. In this story, it's repetitive, acted thoughtlessly by the perpetrators and dealt like the most common occurrence. The story could still be great and progress without those scenes.
Is this one of the author's old work? The fact that it's a one shot and the art looks a bit rougher than their other works.
This work is from 2015 and it’s not one-shot - there are 5 chapters and an extra.
That explains the artwork, it's not bad but it's not as polished as her recent works.