Hope you are doing well and sorry for the trouble. As described, the form fields entered by you manually are printing with adequate darkness and the rest of the form prints light. We need some more information for a better understanding:
- What is the workflow/steps you are doing to fill the form?
- Is this a behavior with a particular PDF file or with all the PDFs? Please try to print a different PDF file and check.
Please try to print the PDF as an image and see if that works for you. Open the PDF > Print > Advanced > Print as Image and see if that helps.
Also, please check for any missing/pending updates for printer driver and firmware and reboot the computer once and see if that helps.