Hello sapo sapo,

this seems like a problem of the “double-pass” printing with the GHOST technology.
It seems like the white toner is not only on the design but also around it…
to check whether this assumption is wrong or is pointing in the correct direction, please check whether the B-Paper is loosing some of its “glue” where no part of th design is.
If the B-Paper is affected looses adhesive in places where there is no toner in your design, then the toner comes from the printing with the printer.
if not please report how the B-paper looks.

FOREVER tech-support team