It was an absolute shit show of lies that nobody really believed. A million people protested https://en.m.wikipedia.org/wiki/15_February_2003_anti-war_pr...
And still, the war went on as usual.
Even if 90% of Russians protested against the invasion of Ukraine I couldn't be sure it would make a difference.
As it is, most Russians don't even see this as a war, just a continuation of the ongoing Donbass conflict.
And mind you, prisons aren’t made equal. Russian ones are on the tough end of the scale.
That plays easily into the common narrative of Americans being bloodthirsty or brainwashed by their media but it simply isn't correct. There definitely was a period after 9/11 when any criticism of the government or war against Afghanistan and Iraq was seen as unpatriotic, the Dixie Chicks were cancelled, French fries became Freedom fries, and propaganda like Courtesy of the Red White and Blue became hits. But the US is more complex than many people give it credit for, and there were also protests in the streets and criticism within the media, even people going to Iraq to serve as human shields[0] against their own military.
[0]https://en.wikipedia.org/wiki/Human_shield_action_to_Iraq