Didn't bother leveling this. When I tried, I made it much worse. So left it alone.
Update: Amaduyu Mitsumi took the time to make it look better. Thank you, appreciate the help! Definitely looks better than when I tried to level it. I tend to leave the grainy type paper alone because it's hard to work with.
@Devildie Thanks for the upload. I took a stab at leveling this gallery. Basically You can find the result here: https://mega.nz/folder/zU0w0Qwa#h9kJbS9IoNTfRG8klhVXVQ. Feel free to update the gallery with it if you find the result acceptable.
Side by side comparison: https://imgur.com/5WQYZh2
Note that for color pages quality 11 JPG should be fine. I provided 2 versions, with and without AI denoise. I personally prefer the denoised version but it's your choice.