I focused on climate change because that is the topic that has the most intensity on HN at the moment. This is a matter of triage. It's incredibly costly in time and energy to write detailed answers like this. We can't do that about everything. If we tried, it would peg us at 100% and starve the rest of the site.
No, HN does not "have an automatic mechanism to reduce the visibility on stories relating to Russia's physical and digital attacks on American democracy". Those issues have received tons of discussion on Hacker News, just like climate change has, just not as recently. If you're talking about something I actually said as opposed to simply making things up, I'd like to see a link—whatever I did say, I wouldn't have put it that way.
That doesn't mean we don't have automated penalties, a.k.a. write software to do things on the site. We rely on software because it would be impossible to do this job without it. There's a lot of software; it does a lot of things. One thing it does is downweight classic flamewar topics. That includes nationalistic flamewars (edit: and partisan flamewars), which there were a lot of about Russia in the last couple years, though the storm of that has shifted to China in recent months. If you're alluding to something I actually said, I imagine that's what it related to.
If you're shocked that some submissions are downweighted by HN software, you may need to realize that this site is curated and has never pretended otherwise. Some submissions are even killed by software outright. The downweights I mentioned are mild and have plenty of opportunity to get overridden, whether by software or by moderators; in fact we do that all the time when we see a substantive story being affected by them. That's one reason why all the topics you're complaining about being suppressed have actually received major, regular discussions on Hacker News.