People need to stop this whole "if you dislike Lamia, you are sexist BS."
Lamia has proved to be illogical several times in the past chapters and this one. She wants her brother to be Duke, but doesn't teach him to be the Duke. Rather she handles everything and gives him busy work. She undermines her brother infront of servants and subordinates, and expects him to somehow take over and be respected. Is annoyed by the vassals concerns even though they are valid, because she can't hear anything beyond her own voice. In this chapter alone, she said she would replace anybody who opposes her pushing her brother to be Duke. Tell me so you think those descenting voice will just roll over and accept it while she goes to the capital to seek revenge? There is a great possibility of a revolt.
She wants to seek revenge on the 2nd prince, but doesn't seem to know the 1st thing about the guy. His strengths and weaknesses, what kind of intelligent strategist does this? Her brother subtlely tell her about the prince's capabilities, but she is so intent on being a mother hen she doesnt hear a damn thing he says.
Now the prince from what we know ain't shit, but jumping to conclusions will not let you win over your opponents. She is so loud and wrong most of the time, that is incredibly frustrating. I don't want an uwu misunderstood prince trope, nor do I even like the guy at present, that still doesn't negate my dislike for Lamia.
All in all people don't like Lamia because she genuinely make no sense, not because she is female. So stop. Like her if you want but stop making it about gender because it is not at least for everyone.
There plenty of female leads that are strong and intelligent without being overbearing and nonsensical at times.