I'm asking here on behalf of my daughter, who has an iMac from 2013, running Catalina; her printer is an Epson XP-6000. When she prints a colour picture, the paler parts come out with a green/blue cast; she's had the iMac/printer combination for a couple of years now and had no problems whatsoever before now.
But here's the thing: the cartridges are all full, the nozzle check looks perfect, and when we "Copy" using the scanner to print directly the same image looks perfect. That says to me that the printer is working correctly, and that there is something wrong with the connection to the iMac (or something is wrong with the iMac) -- but I'm a Windows man so I don't understand the details.
We have tried deleting the printer (including the /Library/Printers/Epson folder), reinstalling the driver from Epson Support, then adding the printer again, and that made no difference.
She says she cannot think of any change she might have made to the printer since the last time it printed properly. She doesn't print every week but she thinks it was working okay a couple of months ago.
Does anyone have any ideas please? I've struggled searching online because the vast majority of the suggestions are to do with changing cartridges, and we are pretty sure that isn't the problem (because it prints directly from the integrated scanner just fine).