In your original post you mentioned the haze on both the windshield and the rear window. If this is the case, and it is the same on both, it may be external discoloration. (and therefore able to be removed by polishing) As far as I know, all rear windows of all Volvos, wherever they were sold originally, are of tempered glass. No internal plastic layer to delaminate/discolor.

Sometimes surface contamination can be removed with steel wool. Use only grade 0000 (aka 4/0) the finest grade there is. Anything coarser can scratch. Give it a try and see what happens. Not much to lose if you're going to have to replace the window anyway.