Is this in the novel?

Yes, it's different.

You're right it's not included in the novel.

So the artist is going rogue to finish the story early i guess

I really don’t like it when the artist doesn’t follow the novel exactly and takes liberty to amend the story, I don’t mind skipping unnecessary chapters but not actually changing it

I mean, as much as I love the novel, they just kept repeating story (?), and it took way more times to make manga. I guess that's why the artist skipped it

I think you need to know the artist doesnt take whole control of which parts they should make in adaption. When novels are adapted to manga/manhwa, theres more people behind the scene than you think. Novel author, editor, producer, artist, artist's assistant and etc.

Because manga takes much longer time to produce than novel, they'll minimize/exclude plots that doesnt seem necessary to not make it a lifelong project. Altho sometimes they do miss important parts just like anime adaption of manga cases. Project that takes too long will take more dedication, process and time, just like ORV, and not everyone is willing to do that with the deadline and stuff. Need to remember these people do have a life beside drawing and writing, they can feel burn out too.

Also there are some novel authors who actually wants the adaptation to have different story because of their change in mind towards how they want the story to progress. For example the anime that has children get eaten by monsters, I forgot the name. Iirc S2 goes on totally different path compared to manga and thats by the author's request.

My point is dont blame the artist lol, this is just the way it works in this industry. No ones taking any liberty and most artist who adapted the mangas/manhwas are so respectful towards the novel author, they actually discuss things a lot behind the scene.

PS. From someone who actually read the author and artist notes on their work