As a trick I also had the option of printing to pdf first and then printing the pdf with okular. However, I think I have solved it, although I have to see if it lasts over time 🤞, I had two drivers: the "driver less" (the one of default printer) and the driver (build from rpm), but I used the "driver less", now I have uninstalled the driver (from rpm) and left only the driver less and everything seems to work better. I understand that's not much of an explanation, but that's what I did.... consider that the brother driver was derived from an rpm and even if I was not using it maybe it created some problems....
Thank you all for the suggestions.