What does a French policeman shooting a child have anything to do with a World War? This is all internal to a single country, and one that isn't even in the top 10 most active in current conflicts.
It's partially a joke made out of fear. A nuclear power is at war with a country in Europe right now. Other nuclear powers are actively supporting the defense of the attacked country. Another nuclear power is very likely to launch its own offensive against a little island it claims is it's this decade. Politicians parroting fascist talking points are gaining power all around the world. You can see the cause for the fear, no?
I mean a state actor gunning down a civilian and getting more public support than the victim sounds pretty linked to the rise in authoritarianism that could very well plunge the world into conflict to me
Such incidents are typically symptomatic of deeper, systemic problems.
Deep, systemic problems undermine the stability of a polity.
Unstable polities are more likely to make irrational choices in an attempt to stabilize themselves.
Such irrational choices often lead to some high-quality international level game-theory style consequences.
When the systemic problems are rooted in a system that is widely used across a swathe of countries, and is systemically failing in much the same way... well... that's a recipe for some 'interesting times'.