I haven't finished 첫새벽 yet, but i can say almost everything is similar (that's why they said it's plagiarism, to something considered to be "plagiarism" maybe atleast 80-90% of it have similarities with other works) and i think the author of 첫새벽 contacting B급 가이드 author's agency first and send a manuscript and point out the similarities and some of readers even notice it and demand a refund from B급 가이드, but they refused it. The situation is kinda chaotic back then..
첫새벽 is a 18+ BL right? Maybe u can't access it because you have to confirmed your ages first to gain access to 18+ contents
So here's the summary
Author 울랄라훌랄라 that made this B급 가이드 (2020) web novel (this manhwa is basic on web novel) plagiarized from author 루하랑 from web novel 첫새벽 (2018). Author 루하랑 actually called another authors to discussed about this similarity but 울랄라훌랄라 deny it and playing the victim card. And sadly, many ppl accused that 첫새벽 plagiarized B급 가이드, even the review in ridibooks has so many hate comments and curse words towards the original author and many ppl give it a low rating.
From 2020, 루하랑 (the original author) always talk about this issue and fight for their rights but 울랄라훌랄라 always denied the plagiarism accusations and even accused 루하랑 that they're the one who's doin the plagiarism... and to make it even worse, in 2021 this B급 가이드 web novel got a manhwa adaptation (poor illustrator have to deal with this shit... I feel sorry for the artists/illustrator)
That's why if you checked this manhwa and web novel in ridibooks, there's none. Cause ridi take it down (unpublished)
It's the article from the publisher:
https://m.blog.naver.com/PostView.naver?blogId=blynue&logNo=223003325490&proxyReferer
And it's the chronology:
https://sisnael.postype.com/post/13856457