Whether it is proven or not does not change the fact that it is perfectly possible, and by the definition you have used around racism, you deny Jews the right to call themselves subject of racism if perpetrated by a black person.
You cannot just designate a whole group of people and give them a big "get out of jail free" card, allowing them to engage racism but not being called out for it.
It is completely absurd to suggest that if a black person hates somebody and hurts somebody because of their skin color we cannot call it racism. Instead it must be given a special new lable unqiue to black people.
What if black people are racist towards another group of black people? Hutu and Tutsi in Rwanda. We cannot call any of that racism because black people are somehow incapable of being racist?
Hutu attacked and killed Tutsi who were those traditionally in power in Rwanda. The marginalized group Hutu, committed genoicde against the traditionally more powerful Tutsi.
By your definition centered around powere structures, Tutsi could not be subject to racism as they were traditionally the more powerful group.
Power and privilege can change. That even applies to white people. You can look at South Africa. Whites look privileged, but a lot of that is simply the privilege that any rich person enjoys. Poor white people are actually some of the worst off people.
This is of course a troublesome topic to discuss as white-supremacist groups will attempt to use such facts to push the idea that there is a genoicde against whites in South Africa. But this is how propagand often works one take a kernel of truth amplify and twist it. That however does not mean it is pure lies. Lies tend to work better when they are based on some actual facts.
You can look at Putin propaganda against Ukraine, where he says he will de-Nazify Ukraine as if the Ukrainian government is a Nazi government. That is rubbish, but this accusation is not made completely out of thin air. Ukraine has long had a significant Neo-Nazi problem.
Thus Putins lies cannot be used to claim that no Nazis exist in Ukraine any more than the tales spun about South African white genocide represents any kind of proof that there is no discrimination at all against white people in South Africa.
This dynamic is not unique. After Nazi occupation of my native Norway, half-German kids got subject to a lot of abuse and racism. When the tables turn former victims are not always very cheritable.
