Same problem with one of my Zenza Bronica ZENZANON PS 80mm f/2.8 lenses. The cemented rear lens doublet is completely milky inside (see photo). The ebay seller rated this lens as "near mint, lens: beautiful condition" 😞 I suspect a previous owner overheated the lens, for example in a car during summer heat. The second photo shows the same element from a (proper) PS 80mm f/2.8 lens of the same age.