A question about Death Note

Aizawa's guess is that the book was replaced with a new one, which means Yue is having a written conversation. There is no doubt about this

1 As for where the new note pad comes from, my guess is that the hotel itself has a spare note pad in the room. The hotel has replaced it with a new note pad every month. I think the newly replaced note was not brought by Yue and Takada, because if it had been brought, it might be of a different style, which would expose flaws, and at that time, Yue had not noticed that anyone suspected him, so he simply used paper from the hotel.

2 Regarding the question of why the mark disappeared when it was left at the bottom, I think the poster may not have looked too carefully. It was said in episode 34 that the note pad was replaced with a new one, not a used one, so the mark at the bottom will disappear.

3 As for why you don’t just use the note paper you brought, I think it’s because Yue is being monitored, and Yue also knows that the female bodyguard next to Takada is N, so she specially prepared the note. It is easy to be suspicious of paper, so it is better to use hotel ones

The above is my speculation, I hope it can answer your doubts