So, what country doesn't try to inject its own agenda in it?

All of them, I dislike how people seem to perceive it, while most of the time, politician job is "damage-control" (which practically means pushing an agenda by ensuring the discourse goes the way they want).

And then, we have the international brainwashing, which is where we think we understand a nation we've never even stepped-in but we don't. Anyone that has been in Shenzhen suddenly can see for themself, most US news don't talk about all the greatness in China, literally majority it is to denigrate the country, news are just so annoying in general and people just love to parrot non-sense (or incomplete non-sense, which is the same thing as not understanding at all), politicians understand that, news understand that.

We can observe Google Trends with Ukraine as an example, when the news and politicians switch-up the topic, then most people just stop caring altogether and move-on and go to the next "big thing", all over again.

Many countries simply don't care about imprinting their official narrative on Wikipedia.