I want to push back on OP's third opinion (this is the only point I am responding to) (I am not a legal expert).
Genocide has a precise legal definition. In the law, there are two primary sources for the crime of genocide: the Convention on the Prevention and Punishment of the Crime of Genocide and Article 6 of the Rome Statute. In both, the requisite elements are:
(1) actus reus—any of the following acts:
(a) Killing members of the group;
(b) Causing serious bodily or mental harm to members of the group;
(c) Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part;
(d) Imposing measures intended to prevent births within the group;
(e) Forcibly transferring children of the group to another group.
(2) dolus specialis—the specific intent to "destroy, in whole or in part, a national, ethnical, racial or religious group . . . ."
Ethnic cleansing, by contrast, is not a recognized crime. Its legal origins are in the International Criminal Tribunal for the Former Yugoslavia ("ICTY"). The ICTY defined ethnic cleansing as "rendering an area ethnically homogenous by using force or intimidation to remove persons of given groups from the area." See here at 33. Importantly, the ICTY's report noted that "[t]hose practices constitute crimes against humanity and can be assimilated to specific war crimes. Furthermore, such acts could also fall within the meaning of the Genocide Convention." Id. (emphasis added). The necessary distinction is that ethnic cleansing, at least under the ICTY's definition, "can be assimilated to specific war crimes", whereas the prohibition of genocide is a jus cogens norm.
Jus cogens norms "reflect and protect fundamental values of the international community, are hierarchically superior to other rules of international law and are universally applicable." See here at 105. This matters because it means that the prohibition of genocide is absolute and applies whether a state is at peace or in war. War crimes, on the other hand, can only occur during war. Is it incorrect to say that Israel is conducting ethnic cleansing in Gaza? No. The problem, though, is that when assessing culpability for war crimes, the calculus is different than genocide. The inquiry is not into whether the crime was done with the specific intent to destroy a group in whole or in part. To evaluate ethnic cleansing (which, notably, has no evaluative criteria because it is not an independently recognized crime) absent this element fails to account for the practices that result in ethnic cleansing. Is it really possible to "render[] an area ethnically homogenous by using force or intimidation to remove persons of given groups" without genocidal intent? I am not sure. What I am sure of is that the International Court of Justice noted that ethnic cleansing may demonstrate genocidal intent in reference to the ICTY's findings. See here at para. 190.
Now, on the question of whether Israel is committing genocide. Regarding the actus reus, Israel has (a) engaged in killings of Palestinians and (b) inflicted serious bodily and mental harm on Palestinians. Israel's blockades of aid as well as its deliberate targeting of hospitals, educational facilities, and cultural heritage sites can be argued to have (c) subjected Palestinians to conditions calculated to bring about their destruction. Israel's attacks on birthing centers may also amount to (d) imposing measures to prevent Palestinian births. This element is generally not contested; it is the second element, dolus specialis, that some argue is not satisfied.
There are multiple ways that genocidal intent can be established. The 2025 UNHRC Commission of Inquiry provides a robust account of facts demonstrating genocidal intent, notable among which are statements from Israeli officials. I will recount a few:
"On 9 October 2023, Israel’s then Defence Minister Yoav Gallant announced a complete siege on Gaza, claiming that Israel was fighting 'human animals' and Israel must 'act accordingly'. . . .
On 13 October 2023, President Isaac Herzog stated, 'it’s an entire nation out there that is responsible. It is not true, this rhetoric about civilians who were not aware and not involved. It is absolutely not true.'
On 29 October 2023, Brigadier General David Bar Khalifa, Commander of the 36 Armoured Division, invoked divine intervention in a call for his soldiers to be guided by general vengeance in their military operation. In a handwritten letter to his soldiers, he said, 'What has been will be no more! We shall go out to it [the enemy] in war, we shall pulverize every accursed plot of land from which it came, we shall destroy it and the memory of it … and we shall not return until it is annihilated, and [God] doth render vengeance to his adversaries, and doth make expiation for the land of His people… The Lord will give strength to his people, and He shall guard thy going out and thy coming in, from this time forth and forever. This is our war, today is our turn. Here we are!'"
Crucially, that "Israeli security forces have intentionally killed and seriously harmed an unprecedented number of Palestinians in Gaza since 7 October 2023" demonstrates that the instructions of officials materialized in a genocidal military offensive. Relevant also to this inquiry is Israel's apartheid regime, illegal occupation of Gaza, the West Bank, East Jerusalem, and the Golan Heights since 1967, and its continual denial of the Palestinian people's right to self-determination. Together, these facts have led many genocide scholars to conclude that Israel has committed genocide in Gaza.