
Possibly. I looked up online the release dates for the manhwa raws for all three, youngest princess, wmmap, and daughter of the emperor and saw that the raws for daughter of the emperor first started in 2015, the raws for wmmap started in 2017, and the raws for the youngest princess started in 2020. I had a hard time looking for dates for the novels but then again I didn't look at some websites directly.
Either way... I partially agree with the other commenter that its hard to claim plagiarism when to me it seems like they were all still different in their own way

Guess what.... I actually found it
https://x.com/yunsulJJ/status/1639292432025100289

1. The wmmap fans who attached daughter of the emperor clearly suck, but i read both works and dont feel like they are so similar ?
Both are daughters of emperors and... thats it? I rly think both stories had nearly nothing in common and there's no real plagiarizing so i dont know where that came from bc even wmmap's novel didn't have similar tropes to daughter of the emperor
Actually i was the real one THAT id say plagiarized wmmap during the 1st chapter. Because of the artstyle erez/lucas and keira falling like athy and the other evil sister trope there was a polemic abt AIWTRO that calmed down as the months passed and then was completely forgotten.

When I read the document the author provided in her post that described the similarities between the two stories, they did seem awfully similar when I read it. When I think of just the stories themselves I didn't think they'd be similar either but the author had found way too many similarities, though they may seem small, that just added up
This comic was plagiarize by WMMAP. The author reopended the case and currently gathering evidences. I am disappointed of WMMAP. This comic was my first child transmigration comic. And I didn’t even realize that WMMAP was actually a copy.