Presuming they didn't just make up their data, imagine you got a call from state TV asking "if you support the special military operation to denazify Ukraine". Your friend just told you they know someone who knows someone who was arrested and charged with oppositing the war for holding up a blank piece of paper in public. Do you tell them the truth?
Edit: Here's an anecdote from Russian social media. A person asks why prices are so unstable. The entire shop looks at the ground, mumbles, and ignores them. Does that sound like enthusiastic support or terror to you? https://therussianreader.com/2022/03/16/dixie/
I don't think it's about "the narrative" though. I've generally seen these polls used by people who self-identity as against the narrative. These polls are usually posted in the comments section to rebut articles arguing (correctly) not all Russians support the war.
https://meduza.io/en/feature/2022/03/07/russia-s-tricky-opin...