Setting Flatten to true on the PrintSettings object merges all interactive form fields, annotations, and layered content into the printed output. This helps ensure filled-in values and visual annotations render as shown on screen.
Flattening is especially useful when printing completed forms or documents that contain overlapping layers. Without it, some printers may skip interactive elements or render them incorrectly. The source PDF file itself is not modified.
Read the Full Guide on Flattening PDFs Before Printing
