My sketchbook scans looked like mud in 2019 and I just now figured out why
Back in 2019 I scanned my ink drawings on a $60 flatbed and the blacks always came out gray and flat, so I just lived with it for 3 years. Then a friend in Portland told me to turn off the auto exposure and scan in color even for black and white work. I tried it on one page and the shadows held detail I didn't know was there, plus the line edges stopped looking fuzzy. Same scanner, same lamp, just one checkbox flipped. What setting did you ignore way too long because nobody told you it mattered?