the land doesn't belong to Israel.
Yes it does. They were attacked and beat their attackers and took the spoils of war.
c'est la vie...
There is a related question I've brought up more than once:
Is Breslau occupied by the Poles?There are consequences to losing wars.
But I do think I understand the position of many of those who say that the "West Bank" is Palestinian land occupied by Israel but Breslau is not German land occupied by Poland. Many people believe in some concept of "international law" which means that these kinds of questions are answered by certain "international bodies" (often offshoots of the United Nations). So the West Bank is occupied because certain "international bodies" say so, and Breslau isn't occupied because there aren't "international bodies" who say it is. I find this to be a scary way to look at the world, outsourcing one's judgement to "international bodies" -- but many people find it more comfortable than thinking things through for themselves.
I don't know enough about Breslau to have a qualified opinion. What are the circumstances that would lead you to question its status as occupied or not? Does Germany contest the land?
Does the civilian population express a German identity rather than Polish? Apparently not. It's Poland's 4th biggest city, it doesn't have a significant German minority and people living there have no interest in becoming a part of Germany.
If we discuss moving the borders and giving everyone back what was taken we'll face a big problem: the restoration point (date).
Your example - Poland fits here perfectly because in 1939 a large part of today's Ukraine and Belarus belonged to them, so you'd have to give back to the Germans but take from someone else.
I'm just trying to understand why anyone would ask if it's occupied. If no one is even seriously questioning it's status, the analogy JJ tried to draw between Breslau and Palestine isn't valid. Perhaps then the reason no international body has deemed Breslau occupied territory is because there's no basis for it because nobody is disputing the territory today.