I'm okay with them being happy and a bit on loud side. What I'm not okay with is when there are groups of 50+ teenagers on vacation who decide to be rude and pushy, and the chaperones who don't seem to give two craps about actually chaperoning.
Case in point, when I was at WDW back in July 2019, a group of them were disembarking Living With The Land....before the boat had even pulled in to the station.
I don't think it's "Brazilian Culture" as many have alleged; in fact, I suspect that if you had large groups of wealthy-class teenagers traveling on vacation to another country with little to no supervision, they're going to run amok regardless of where in the world they're from.
It just so happens that these groups of teenagers just happen to be from Brazil.