I have a normal pdf file with no background, just text. When I print it in grayscale mode, adobe reader adds a gray background to the page (attached picture). If I print the same pdf file with Microsoft Edge in grayscale, there is no such background, as expected. So there is no problem with the pdf file, or the printer, or the driver. This issue also does not exist when I print the page in adobe reader in color mode; it only happens in adobe reader when I print in grayscale mode.
I tested various settings in the advanced print setup menu, including "treat gray as K-only grays" and "preserve black". none of them worked. Also, in the accessibility section, the "replace document colors" option is unchecked.
I am using Windows 10 and I have an HP MFP M277dw laser printer. My adobe reader and HP drivers are all up-to-date.
This image shows the top left corner of the page. the gray background is added to all of the page and it's quite prominent.
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