That escalated it a lot, but the protests and strikes started way earlier with a pension reform that kinda robbed the people of 2 work-free years. And it wasn't even that applicable to most of the population, instead it unfairly targeted those who held some of the most physically demanding or damaging jobs. Macron doubled down, and then that traffic stop killing... so yeah, it's really not surprising that it escalated from there.

What didn’t help is that police has a long history of violence in general, see this article from 2016, for example. It’s been like this for a while.

There is currently a climate of defiance of our government in France. So I guess every little thing can just light everything up unfortunately. My other comment is more explicit on why we are in this context.