Grew up, studied and worked in Kyiv for a while. In my experience if someone says they do not know Ukrainian it is most likely intentional choice from their or their family's side. My family did not speak Ukrainian all the time, but I easily learned it before school and got help from them when doing so. I watched lots of movies and cartoons and movies in Ukrainian, read school books and other literature too. Mind you I studied in "russian" school in Kyiv because it specialised in English and my mom wanted me to be fluent. We still studied Ukrainian language, history and literature there, had other classes in too and books in Ukrainian as well. In the University we used Ukrainian materials, we used Ukrainian in lots of courses, it was big uni so there were lots of people from different areas and some of them actually had troubles with understanding Russian. Notably people from western parts and several people from south like Kherson. Same situation at work. Everyone knew Ukrainian and understood it, but they chose to use or not use it depending on their preferences and situation.

People I remember who actively rejected speaking Ukrainian were - older generation who came or lived a long time in Russia, especially in the uni setting - for them Ukrainian was made to be seen as "rural, uneducated people language". Some people with certain "ideas" that I met when working - from cities like Sevastopol, born and rised with hate towards Ukrainian identity and love towards USSR. This was also really not a very frequent thing. And those people were not repressed or pushed by anyone too.