Just like in France: a planned and legitimate protest turning violent near the end, clashes with the police escalating into riots after hours of tensions.

Here, there was no context to the riots other than "go to plaça Catalunya and break/steal things", no political demand whatsoever, it was a totally opportunistic chaos and nothing like I've seen in France or Spain ever.

A great many riots result from building pressures and real issues that formed over months or years.

  In the preceding months there had been growing unease between the police and the inhabitants of ...

~ https://en.wikipedia.org/wiki/1981_Brixton_riot

Which is pretty different to this apparent clear blue sky bolt from blue spontaneous remotely weaponised flash mob.

Lots of social unrest on every online platform, for example what happened in the days prior to 15M (which thankfully didn't end up in riots, but riots would have been another logical outcome).