Annoyingly, I am currently trying to print a filled-form PDF with FF and it is not working. When I try to print the page, it comes up with the form without all of my filling. So, treat my previous comment with suspicion. mrc
I just used Firefox 140.0.4 on Debian 13 (sid) to download a 1040 pdf from https://www.irs.gov/pub/irs-pdf/f1040.pdf; the tax form opened in my Firefox window, and allowed me to click in the Last Name and First Name fields, and put in my name. I then "printed" the document to a new .pdf file, and from a terminal window was able to use evince to open that new .pdf, and it still contained my names in those fields.
I didn't try actually printing to a printer, though.
-- Kent West <")))>< IT Support / Client Support Abilene Christian University Westing Peacefully - http://kentwest.blogspot.com