Why are posts supporting Russia banned on HN?

Although some of the measures that are being taken against Russia are likely to cause discomfort and perhaps harm to the civilian population there, the community here believes that they are necessary currently in order to put pressure on problematic leadership.

The way that manifests is that some/many users will flag and/or downvote posted content that supports Russia.

There certainly are people stupid/ignorant enough to believe Putin's invasion was provoked, but it's more likely to be part of a state campaign instead.

The vast majority of humans aware of this conflict (including in some Russian-allied countries) are opposed to the invasion, so we would expect English-majority websites to reflect that ratio absent manipulation.

I don't know what specific posts you are concerned with, though.

You should accept the US world's vision and adopt its mindset or being banned, ostracized, canceled, whatever.

In the US vision, wars are something bad only if it's not aligned with US interests or isn't executed directly by US. In this particular case, Russia invading Ukraine goes against US interests.

In short, US give to themselves the rights to do whatever they want to achieve their goals, including wars like in Iraq and Afghanistan, while condemning everybody else that try to do the same. You should accept or face the consequences.