The UN definition of genocide requires acts of violence with the "intent to destroy, in whole
or in part, a
national, ethnical, racial or religious group,
as such" (emphasis mine).[1]
Putin and Russian have made it clear that they intend to destroy the very idea of Ukraine.
For evidence of this, see[2], a book which has been used for the last 3 decades to indoctrinate individuals in the Russian government.
The existence of this book, and the fact that its author, Aleksander Dugin, has Putin's ear (and has even been called "Putin's Brain"), is evidence of the intent behind the invasion of Ukraine. In the eyes of Russian leadership, Ukraine does not exist.
To realize their goals, Russia does not need to kill all of the people of "the Ukraine" as they call it. Instead they must accomplish the erasure of the concept of Ukraine as a separate nation, people, and culture.
In other words, they must "destroy... a national... group, as such".
Therefore, according to the definition given by the UN of the term "genocide", the Russian war in Ukraine is genocidal.
All arguments that I have seen to the contrary point to the lack of intention to kill every Ukrainian. As shown above, killing everyone in a group is not required to constitute genocide.
I'll go one further. Here's the definition of "genocide" from Oxford:
"The deliberate killing of a large number of people from a particular nation or ethnic group with the aim of destroying that nation or group."
I don't think this could be simpler.
The Russian war in Ukraine is genocidal.
[1] https://www.un.org/en/genocideprevention/genocide.shtml
[2] https://en.wikipedia.org/wiki/Foundations_of_Geopolitics