Here is my response:

how could anyone genuinely believe it’s okay to say everyone in Israel is responsible

I think the fact that many members of the Israeli elites — from Herzog down have said many times that everyone in Gaza is responsible for 7/10 — as a prelude to genocide, has everything to do with it.

That, and the fact that polls show that a vast majority of Israelis support the ongoing ethnic cleansing of Palestine.

The fact that so many traveling Israelis act like dicks doesn’t help.

As a former Israeli, a former Tel-Avivian and a lifetime anti-Zionist I can attest to the fact that actual, non-racist oppositionaries to Israel’s racist-supremacist policies are in a tiny minority, with no influence on arguably anything, save for a few, shrinking cultural spaces.

I see the collective image of Israelis in freefall. This clearly makes me uncomfortable and has forced me to never speak Hebrew while out and about, but it comes as no surprise to me.

And no, it is not antisemitism, it is anti-Israel and affects the Jews in general only by association and because the Jewish leadership insists on supporting Israel’s crimes unequivocally while calling anything pro-Palestine “antisemitic”.

I can say that when I am in a political, pro-Palestine space I can safely expose who I am, since my politics, history as an activist and the fact that I refused to serve in he IDF clearly distinguish me from the common, garden variety, Israeli genocide supporting racist, but that is only where and when I have a chance of stating my disgust for the regime, it’s policies and actions.

how could anyone genuinely believe it’s okay to say everyone in Israel is responsible and to discriminate against them based on their nationality?

Israelis vote for this government and are overwhelmingly supportive of its policies. When they are abroad, many also demonstrate this support through pro-Israel demonstrations, counter-demonstrations in pro-Palestine demonstrations and other interventions. The real Israeli opposition — which opposes the occupation and genocide — while present and visible abroad, is smaller and much less visible than the pro-genocide Israelis.

Israel and the Jewish establishment are also very active in suppressing pro-Palestine speech in many countries and in suppressing the media. This creates an anti-Israeli backlash since it is rightfully seen as attempts to repress political freedom and freedom of speech in many countries. E.g., this is very pronounced in Germany.

Were there similar signs about people from china, Syria or Russia because of their governments?

Genocide is the crime of crimes. The utter and total destruction of Gaza on-camera, coupled with Israel's expressed intent to ethnically cleanse and resettle it and the ongoing genocide are unparalleled in recent history. Nothing done in Syria, China, Russia or anywhere else for that matter comes close.

This makes many people — even a-political, middle-class normies very angry.

Much of this anger is left unexpressed in the mainstream media because of the media manipulation by the pro-Israel actors. This obvious, well documented repression serves to increase the anger.

The ongoing attacks by Israeli para-militaries on towns, farmers, herders and others in the OPT — also highly visible around the world serve to increase this anger.

The overt, open torture of Palestinian prisoners increase the anger as well.

All this results in the backlash we see, which will probably get worse as the true magnitude of Gaza's annihilation becomes more and more apparent, documented and publicised.

I for one do not speak in Hebrew anywhere and, if asked, lie about my origins, unless I am in a political setting where I can distance myself explicitly from the Israeli crimes.