Subjects can often connect to each other, though. Depending on whether we're talking about a formal debate with a specific, limited topic - or whether it's in the realm of open discussion, the topic may evolve or shift over the course of the discussion. That often happens, and it can be quite normal within the natural flow of a discussion. I wouldn't automatically assume some attempt at dishonesty (although I wouldn't automatically dismiss the possibility either).
As for the example you give, I think it depends on the context and the specific objective one might have in initiating a discussion.
If you mention attacks on schools and hospitals by Putin's army, is that merely an attempt to inform, just like people might post news stories in the Current Events section? If so, then that would merely be a recounting of events, not necessarily a topic of debate. Some people might see it as "war news," which has sadly become relatively commonplace in our time.
As a counter-example, I recall an online discussion around the same time that the U.S. invaded Afghanistan back in 2002. Someone posted a picture of a baby at a hospital being treated for injuries from an apparent U.S. attack. It was done in the context of criticizing and impugning the reputation of the US government, as if to say "You devil Americans! Look what your troops did to this poor innocent baby!"
Are you suggesting that it would have been dishonest or dishonorable to respond with the reasons why US forces attacked Afghanistan? People might have responded "What about 9/11? What about Al Qaeda? What about Osama Bin Laden whom we believe to be hiding in Afghanistan and protected by the Taliban?" Of course, the baby in the picture had nothing to do with any of that, but if one insists on focusing solely on the injuries inflicted by the U.S. military and considers anything else to be "off topic" or an "attempt to change the subject," then I might find that to be questionable.
But to post a picture of a baby as a victim of American bombing would imply a claim that the entire reason for the American invasion of Afghanistan was to bomb some poor baby in Afghanistan's interior. I don't think that puts much clarity on things, nor does it really explain why it's happening or what's actually going on.
Now, in the case of Russia's invasion of Ukraine, the current narrative is not just a recounting of events. We've been getting quite a bit of war news out of Ukraine these past weeks, but the overall topic regarding the relations between Ukraine and Russia - and the West's involvement in the situation, including the expansion of NATO - that's been going on for years - decades, in fact. There's a long history and quite a bit of background to consider.
This is not a simple matter which can be easily characterized by the standard rhetoric of Western sanctimony, which is the main cause of anti-Western sentiment throughout the world. Our hypocrisy has been our greatest flaw, and it's the primary cause for the decline in the West overall. Too many people in the West refuse to see this, and they think that our problems are caused by other things, other nations, other ideologies.
As for Ukraine, I don't know if @Estro Felino is correct about Soros' influence. I'll admit I'm somewhat agnostic about all that, but I suppose anything is possible.
But on the other side, I've also seen many people compare these events to Hitler's invasion of Poland, along with claims that Putin is trying to restore the old Soviet Union, which would also appear to be unevidenced conjecture and speculation. Putin has already stated his reasons for invading Ukraine and has also stated his conditions for peace. It's up to Ukraine and NATO to either accept those conditions or not, though it seems they've already made their choice here.