The file was moved during scanning.
If the resolution setting in the scanning options is incorrect, the higher the scan resolution, the sharper the image.
The resolution of the printout is set incorrectly, and the file size is set incorrectly.
The scanned manuscript is not clear enough, and there is dirt on the glass manuscript table, which will make the scanning effect worse. It should be cleaned in time with a paper towel that can't get rid of debris.