Many middle class lycéens know what they are protesting about and go about it in a peaceful way. More lycéens don't care but see it as an opportunity to protest in general and have a day off school. And then we got the violent rioters; some of them in school, many not even in the education system but just want to brawl.
And all of these take place in the same space, overlapping, so it’s hard to tell them apart until it goes tits-up.
in the first couple of days at our lycée we had the respectful, peaceful protestors outside. French-style though so the entrance was solidly blocked with big bins / barriers. They were then baited and encouraged to fight by some of the ‘anti woke’ students (lots of the first group are also pro Palestinian and turn up wearing scarves etc) which resulted in scuffles. Then the guys in black wearing mask turn up looking for a fight. Some of them are students from other (poorer) lycée in neighbouring areas, some seem to just be on a rampage. And they are swiftly followed by the police /CRS at which all bets are off, safety wise.
as @TheBlueKoala says, the 2nd and 3rd generation immigrants have a point. France is a highly elitist, very racist country. The state is officially blind to colour / race / ethnicity but people / teachers / employers / police are not. It just means there’s no data to back up claims of racism.
And the policies of assimilation (not integration), and laicite means these groups feel very alienated from French culture and society.