Students have started protesting poor conditions in public schools, such as lack of insulation causing horrible cold and heat, presence of rats, etc. When the kids started protesting they were attacked by cops. Things like rubber bullets knocking out teeth and breaking bones and stun grenades causing burns and even blowing off a teen's hand.

The cops are also allegedly ranting about how they're looking forward to putting the kids in their place, as pigs are wont to do.

Naturally, reasonable people (particularly parents) don't like when kids are being maimed for peacefully protesting. This led to adultsjoining the protest to protect kids and the police kept escalating until the whole thing turned into a riot.

The protest origin was a push by teens for more teachers in schools, smaller class sizes, and repairs to thousands of rotting buildings. Many adults joined in solidarity very early, including Frances left wing party.

French police cracked down brutally on these children, including firing a tear gas canister at point blank range into a 15 years olds face, shattering his jaw and all of his teeth, and blowing the hand off another teenager with a concussion grenade. Only after maiming these teens did the French minister in charge of police temporarily limit just concussion grenades, all while applauding the police response. This was seen as pretty tone deaf, and enraged a lot of people.

After weeks of rioting, including blockaded and some burned school buildings and thousands of arrests of teens, Frances prime minister said they would add 3000 teachers to schools as soon as possible, and work to fix other issues. This was seen as to little, to late by many. As the article says, the protest is now widening in scope among general unrest with French's centrist, neoliberal government.