I just watched it and I thought Jacobs won it by 2 rounds. Considering GGG won a 10-8 round, that's pretty conclusive. But having said that, there are many ways to score a fight and I wouldn't say it was a robbery .
I think it's a lot of factors all adding up to what happened, GGG isn't getting any younger, he struggled to cope with a bigger, stronger guy, he didn't cut down the ring as well as he normally does and he looked a little ponderous.
The one good thing is that we now have a definitive idea of GGG's Level. He's no ATG, but he is a very respectable champion, who was maybe exposed a little.
Despite the fact that I think Oscar is a wanker, maybe he's timed this just right for his guy. I'm still not sure though.