Lemkin based the crime of genocide on the Armenian genocide and the colonial genocides of the Americas, not on the Holocaust. His intellectual breakthrough (that the extermination of those peoples could be understood through systematic destruction and perceived membership of a group) came in the 20s and 30s. Indeed, in discursive scholarship generally (more-so contemporary scholarship than, say, latter-half 20th century scholarship), the crime of genocide is not understood in terms of the Holocaust. In his autobiography, Totally Unofficial, Lemkin recalls how he urged his family to flee after the invasion of Poland in 1939 because he could see how the crime that he had spent more than a decade developing a framework for was being perpetrated against the Jewish people of central and eastern Europe.
The Holocaust, the Shoah, is by far and away the best researched genocide, and Shoah scholarship is central to genocide scholarship in general: you can't do a genocide research degree without a focus on Shoah research, for good and obvious reasons. But the crime of genocide, both in its codification in the Genocide Convention, as well as in discursive scholarship isn't purely the codification/scholarship of the crime of the Holocaust. There was a while - and you can see this in the focus of genocide research scholarship in particular from the 1970s through 1990s when Holocaust research was front and centre - when comparative genocide frameworks were popular; understanding different genocides through how they compare with other, as yet better understood genocides. The temptation, then, is obviously to consider the best researched genocide to be paradigmatic. And certainly within public discourse, the Holocaust is considered to be the paradigmatic genocide. But this is to erase both Lemkin's original work, as well as to risk misunderstanding and delegitimising other genocides which don't-look-enough-like-the-Holocaust.
Genocide exists as a distinct crime. In a way, as other posters have touched upon, it can be understood as a systematic web of other crimes, given that those crimes are carried out with the overarching intent to destroy in part/as a whole a distinct (protected-identity) group. To prosecute those responsible for the individual crimes that together constitute genocide is one thing, and is a way of bringing the perpetrators to justice. But to prosecute the genocide as a whole is to do greater justice to the victims of genocide. It is very important that we do not shy away from calling a genocide a genocide. And for this reason, it is vitally important that we call Israel's genocide of Palestinians a genocide.
Israel is committing genocide in Gaza. There will be antisemites who relish the opportunity to call Jews genocidaires. There are people filled with racist hatred who will pervert anything to their own hate-filled ends. But it is specious to suggest that their messed up motivations cast doubt on the motivations of nearly every major international humanitarian organisation (who all find that Israel is carrying out a genocide) as well as the general consensus among genocide scholars. Many of the articles on the Journal of Genocide Research are available to read without institutional access/without paying. We don't have to guess at their reasons for calling the Palestinian Genocide a genocide. They tell us their reasons in their work.
The fact that there are antisemites who, through their own commitment to Zionism, want to call Israel genocidal because it means that they feel they get to call Jews genocidal - and, of course, it is deeply antisemitic to conflate Jewishness with Israel - does not mean that we ought to be careful about calling the Palestinian Genocide, perpetrated by the state of Israel, a genocide.