How many Arab nations allow Jews that migrated to Israel back to their countries? Or are Arabs allowed exclusionary policies and only Israel has to be different to not be labelled as "apartheid" by the woke ones?
Well, largely because the Arab countries are not. They do bad things, yes. They did a one-time expulsion of Jews, which is now no longer on going. They have highly discriminatory immigration policies. They have abusive "guest worker" programs that end up as de-facto slavery for many. These are pretty bad things (though discriminatory immigration policies is pretty uniform, the world over), but these things are not generally what people mean by apartheid.
It's not fully fair to describe Israel as apartheid either. Its actual citizens largely have the same rights on paper no matter ethnicity or religion (though the religious marriage laws are an oddity, and the inability to intermarry does make it comparable to those prohibiting interracial marriage in South Africa).
But it is actually somewhat fair to compare Israel to apartheid South Africa. They have an active, ongoing separation of populations into segregated areas and even nominally independent states, that have no effective autonomy due to the overwhelming power and actual physical control of Israel. The Gaza strip and the West Bank are nearly direct equivalents of South Africa's bantustans. If you accept that Israel does have real sovereignty over all the territory it occupies, the differences in how it treats different people really don't seem just.
That likely would have spared them comparison to Apartheid, yes, but would instead have been an ethnic cleansing.
The unfortunate matter is that the Arab states were not criticized harshly enough. And that is almost certainly due to a combination of antisemitism and realpolitik over their oil resources. And this relative lack of criticism continues to this day.
Nonetheless, it's still not a responsive defense to bad behavior to point out other bad behavior that is less criticized. By all means do what you can criticize these states and surface their bad behavior (and do so individually; they're not a monolith). But a thread talking about Israel isn't the place to do it. First of all, it's ineffective, second of all it's derailing to the thread.
When rules are applied selectively and one nation is singled out for bulk of the vitriol, it's 100% valid to ask why someone else wasn't penalized for doing something much much worse. And you're right, most of Israel bashing is antisemitism.