All research? I don't believe it. That percentage is just Putin's propaganda and nothing else, there's no way in hell that 80% of Russians support the war. After all, can you really trust any polls that are coming from Russia, given the circumstances? Their elections are heavily rigged for decades, let alone something like polls in the middle of war.
Even if it is not 80%, not every survey, even outside Russia, can be Putin's propaganda. The fact is that the vast majority of the 150 million people see nothing wrong with their country doing aggression against another country, and remember what it was like in our country in 1991 - is there a difference in the minds of the people who started the bloody war then and now with the aim of occupation and ethnic cleansing?
Here is a survey of 3000 Russians that shows how they think when asked a direct question and how they react when asked differently.
https://blogs.lse.ac.uk/europpblog/2022/04/06/do-russians-tell-the-truth-when-they-say-they-support-the-war-in-ukraine-evidence-from-a-list-experiment/