Most Russian assets have been frozen, not seized. The German subsidiary made news for being an exception in that Germany took control of the subsidiary. But it’s still Gazprom’s property.
> That is my understanding. The property still belongs to the owners
IIRC, there are efforts being made to outright seize stuff like the yachts, sell them, and give the proceeds to Ukraine. I'm not completely up on the details, though. I think some criteria might be if the property is de-facto owned by the Russian state, or was acquired due to corrupt association with it.