Everybody starts out inundated with liberal propaganda and concept framing. You read the articles about these scary armed separatists and the people they've killed, and why they're so unreasonable to not be accepting the Legally and Internationally Recognized State And Borders™.
For anyone who digs a bit deeper, and has a tightly-held value of self-determination, they notice that the separatist areas are overwhelmingly Russian-speaking, had very distinct and persistent voting patterns compared to the northwest of the country, and didn't have the same historical connections or associations with the rest of Ukraine. That's when the narrative starts to peel apart, and there's room to wonder "what if they're not aggressors, what if they had legitimate concerns all along". Add in a bit of great power conflict analysis and it clicks.
