More superficial observations … 
Judging from the photo of the new case(s) …
… and comparing it with the out of stock (old) battery …
https://shop.fairphone.com/media/catalog/product/cache/3/image/560x/602f0fa2c1f0d1ba5e241f914e856ff9/b/a/battery_3.jpg
… it seems that both the FAIRHONE lettering on the battery disappeared and the lift here symbol changed on the battery. I would also suspect that “Change is in your hands” is printed on the (new) battery and not into the inside of the new case.
Watson?