5. Dirty optical path. 5. Not sure what that is? The optical path from the light source of the scanner/the film being scanned/scan sensor when scanning a piece if film.
6. Bad cable/connection to the scanner/computer. 6. Any way to test this? Replace the cable, use a different socket on the computer or both.
This suggest that the banding exists on all scans but only becomes evident on some negatives.
I'm running Win 10 2H2 on a Dell Precision laptop. Older scanning programs that would not load on Win 8.1 or early versions of Win 10 now run.
Try the Canon software that shipped with the scanner, downloadable at
https://www.usa.canon.com/internet/...rt-scanners-canoscan-series/canoscan-fs4000us and give it a try, it should run on Win11.