Cliff observes that in Poland, where there are many migrants from Ukraine, all of the ads and signs targeting Ukrainians are in Ukrainian, even though most of the migrants speak Russian to each other.
It is, indeed, a somewhat paradoxical situation where Ukrainians whose primary or only language is Russian, feel offended when addressed in Russian. I’ve had people tell me in Russian, “And then they came up to me and addressed me in Russian. The gall! I completely ignored them.”
Ukrainians these days find it very important that others recognize them as not Russian, as different from Russians, and repudiate all attempts to address them in what is often their only language.
When a stranger addresses me in Russian (for instance, a visiting scholar at my school), I turn standoffish and unpleasant. But if they talk to me in Ukrainian, which I find extremely hard to speak these days, I become the nicest person known to humanity.