I can relate to this a lot. I'm an Australian who lived in Russia for 7 years, 6 of those in Krasnodar. Krasnodar was founded by Ukrainian Cossacks at the time of Catherine the great. Around Krasnodar they speak kubanski which is about 70% Ukrainian. I chose to study that local and mocked dialect and so understand Ukrainian pretty well. In Krasnodar, the new arrivals each year from colder areas of Russia, make kubanski almost non existent except for a few taxi drivers from the villages. I studied Russian at university there but I tried to speak Kubanski as much as possible. The irony was when it came to karaoke, Ukrainian songs were incredibly popular.

I then spent the last 6 years in Georgia and married an Armenian born in Georgia. The Armenians were often teased and bullied at Georgian schools for not being Georgian enough. There were two school systems- One Russian and one Georgian. So the Armenians, by and large, sent their kids to the Russian schools. Most of these Armenians in Tbilisi could speak Georgian too but most of them had lost their Armenian language or knew just parts. So my wife grew up as an Armenian in Georgia with Russian the language of the home. Both her and her parents are fluent in Georgian. Her father can also speak Armenian well, her mother quite a bit less. My wife understands just a handful of phrases from speaking to her grandma. Our son goes to one of the few Russian schools left, most have converted to Georgian. We are trying to bring his Georgian level up as it is important for the future.

For me, there are some interesting parallels and nuances between Georgia and Ukraine. Some stats for you:

1)In Georgia 65% of people speak more than one language. Of those who speak just one, the vast majority it is Georgian only. But there are regions in the south where Armenians and Azerbaijani speak only their native tongues and other small groups like Dagestani have villages too.
2) of the 65% who speak more than one language, 88% speak Russian. 18% speak English. Now if you talk to many young Georgians they will be indignant with these stats and insist English is more widely spoken. But that's by living in a bubble. 33% of Georgians of middle class and above speak English, only 5% of the poorer classes do. 45% of people under 25 years old speak English too. So if you speak English and say all your friends do too- chances are you are young and come from a middle income family.
Outside or Tbilisi, the level of English drops to near zero and the percentage of people who can speak Russian(though may not use it in daily life) gets close to 100%. Thus I, who speaks Russian, could manage living in rural areas easily. Of course this ease slowed my progress in learning Georgian. Georgians don't like to admit it for nationalistic reasons and fair enough and maybe Russian will be all gone in a generation or two. But even the young overestimate their English and underestimate their Russian. They often use Russian slang, up to recently films were shown at the cinema in Russian too, and they listen to Russian music.

Georgia went through the same russification process as Ukraine, migration of Russians was encouraged in the Soviet Union and Russian was the language for paperwork and business. Ukraine is not unique in trying to wind back this colonial and imperialistic era.

Even in far flung Uzbekistan where I lived even before that and where my daughter still lives, we can see this change. And my daughter and her family are Crimean Tatar, the family originally expelled from Crimea to Central Asia, and Russians moved in to replace them. What language does my daughter and her relatives speak? Hint it isn't Uzbek, it's Russian. Yet in Uzbekistan they switched from cyrillic to Latin based characters for Uzbek, banned Russian companies investing(they still do through shelf corporations), and made Uzbek the one and only language. The mother of my daughter, when the mother was alive, knew Uzbek fluently but refused to speak it and only spoke Russian. For that she paid more at the market and every taxi ride. Russians there told me to have nothing to do with the Uzbeks and I wouldn't be accepted etc. Well, I learnt Uzbek and it opened up a world to me. I was treated like royalty and I got Uzbek prices for everything. I mention this as one of the key propaganda arguments when I was in Russia was that Ukraine was suppressing the Russian language. But as you can see, from Georgia and Uzbekistan(and can see in the baltics too), this has been a largely universal process, not a Ukrainian process, to shake off the shackles of Russian imperialism and cultural assimilation and to take some pride in native languages suppressed by Russia for so long. Sorry for the novel of a reply.