I haven't read past chapter 17, bsc I planned to drop this manhwa. But I think the first and most bigger plot hole is how the hell the scientist lady lost her most precious squirrel lab test? She said it herself that the fl is different than other devine animals(?) Test lab, but somehow no one knows fl is an important lab test and sold her?
Also the pacing is also super weird, for example in that dinner scene, they were talking abt the lost child, but instead of showing this part like a normal manhwa, they cut off this convo, and then show it again to us as a quick flash back - also isn't it rude to bringing up other family's taboo topic? - other example, after the duchess mistook fl as her daughter, they just skip days after that and we just shown, like, maybe 3 panels of they bonding? Idk how long it's been since fl being recognized as yurika!
last thing, I don't want to sound like a bitter hater but the artstyle isn't that pretty as well don't get me wrong, I've seen a lof of worse artstyle,but this one is just decent
Completely forgot to add, I 1000% agree with your first point, idk abt the other ones since I haven't read until that part yet lol
That point is also a very annoying plot hole, as if AI generated this story (i'm not accusing the author of using AI i'm just saying the plot holes are so clumsy and damning just like how AI generated story)

I think the author wanted to make everyone play 3D chess and engage in a battle of the minds but there were so many dumb things in it from start to finish that I literally rolled my eyes sometimes.
here's just some of them:
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1. the children of the medest family go missing every generation and instead of connecting it to the family that was killing their vassals, the family just ignores it?
2. all the children go missing and so they sent one guard with their 2nd born daughter to her baptism?
3. the evil lady gets a chance to go back to her secret lab and she only steals some of her research but leaves the dad alive? Why would anyone leave a loose end like that? And if she had one more mind-control potion, why would she give it to yohan instead of giving it to the tiger and telling it to kill any medeste that might come through?
4. "hey guys our kids are disappearing so we're going to give the family heirloom destined to save us to someone else"
5. no knowledge of anything is passed through the families?
6. etc etc etc
just dumb lol