It is not even remotely "anti-Zionist" (and certainly not antisemitism) to be horrified and disgusted by the way the Palestinians have been treated, and particularly those in the Gaza strip.
I have zero connection to either side. I grew up where there were no Jewish people and no history whatsoever of antisemitism. There were no Palestinians either and no one even vaguely associated with them. No on knew enough to have a problem with either side.
When I went to the USA, my roommate was doing a PhD on Palestinian childhood. She had to visit the Gaza strip and West Bank each summer for years for her research and still does now that she's a professor. Her reports were deeply shocking, with people routinely being forced to queue for hours to get through crossing points for jobs and to see family members in other Palestinian areas, supplies being cut off, routine bombing of civilian areas, and on and on. Conditions in the Gaza strip are horrible right now, but they're not much more horrible than they're always been.
Of course the attack on Israel that just happened cannot possibly be justified. It was horrific. It was also inevitable and it's surprising similar attacks haven't happened more often. We would not accept the kind of life that the Palestinians have had for generations now since their land was taken.
There's no perfect solution at this point, but at the VERY least, the Israelis should be stopped from oppressing the Palestinians. They should not be allowed to blockade necessary supplies or create daily misery for people relying on jobs or wanting to see family and friends in the West Bank/Gaza strip. Palestinians have traditionally had fewer rights in Israel and that's wrong.
There are people here saying that if the Palestinians were given their own country, things wouldn't improve. That's lame excuse-making. Of course they should have their own country. I think the Gaza strip should go to Israel and an equivalent or larger area of Israel added on to the West Bank so that the Palestinians aren't cut off from each other. It should go without saying that Israeli settlers should get out of Palestinian areas. The USA has added fuel to the fire by supporting the Israelis when they've encouraged settler encroachment.
I think many people my age see the Israelis as the aggressors and if the Israelis don't change, they're going to find that support from the US disappears over time as we get older and the elderly people who enable Israel disappear.
What Hamas has done is utterly evil and wrong, but desperate people do desperate things and ordinary Palestinians are being punished for it. The situation did not have to get to this point.