It is a war and most sources are biased. If you specifically look for stuff contradicting mainstream and mainstream is supportive of Ukraine, you will mostly find mostly pro-Russia stuff. That won't tell you what is wrong or not.
It would be better to look specifically for sources that should be uninvolved neutral or for sources from places that are near the action and have active independend press.
Have you, by chance, noticed how even most Russia allied countries are not willing to repeat the Kremlin propaganda ? Or how those events are reported in neutral nations ? Or how every Ukrainian neighbour country sees it ? Have you noticed how many formerly Putin-friendly politicians and pundits all over Europe are not willing to follow his arguments this time, shattering whole political parties ?
As for the Russian assertions : Have you looked whether any left-wing or antifascist movement that is not overly Russia friendly has ever complained about Nazi influence in Ukraine ? Have you ever seen people from the Russian diaspora complain about suppression of Russians in Ukraine ? Have you ever seen NGOs trying to help the poor ethnic Russians in Eastern Ukraine or even try to pressure Western nations to do something about supposed Ukrainian crimes there ? The lack of anything about any of that is not traceable to Russian sources makes it clear that there is no or only little substance behind.
US anti-mainstrem groups are very vulnerable to propaganda because people only contrast with mainstream media and if it is different, they believe it. Because it takes time and effort to check your sources/ contrast with others. Obviously it also helps speaking several languages, but we are in the time of having access to everything on the internet and being able to use google translate. If you really wanted, you could research your stuff.
The US has been somewhat insufferable after winning the Cold War and did things that could count as provokation (mostly around missile defense). But that is many years ago (they got humbled in Afghanistan and Iraq) and it was the US and not the Ukraine.
The only provocation from Ukrainian side is basically "existing" and "going a different way from Russia, seeking economic benefits from joining EU instead of trying to revive the Soviet Superpower and its influence". You could call that provocation, but, well...
As for Putin as the next Hitler : Putin does not have plans to exterminate hundreds of millions of supposed subhumans to get his racial pure utopia. That is quite a big difference.
But everything else ? Well, they seem quite similar when it comes to killing political enemies, accepting collateral damage, running the economy and frankly, Putin has less justification to invade the Ukraine than Hitler had for Poland.