... for me (Austrian ProfHunter) it's deffinately no European stag!!!
That’s interesting, we see antlers like these in Poland on Red deer every now and again and @mark-hunter mentioned they see them in Croatia. Mixed, non pure blood gene pool perhaps? The long tines are unusual but I’ve seen Reds like that over here.
As for the colour, few years ago I was helping my grandpa clean his shed and we found a single antler that is white/pale like that. He wasn’t sure when he had shot it, perhaps in the 50s. It’s not a large antler, maybe strong second head or average third head. He had no clue as to the treatment it may have received. They were poor people in a country ravaged by war so meat mattered, antlers not so much.