Cortis shouldn't be immune from criticism just because they're teenagers.
To be clear, I don't think their looks should be discussed at all, minors or not, so that is not what I'm talking about here.
However, I do think criticizing their music and to a point their actions is fair game.
Any time someone says they don't like a song by Cortis, you can count on the responses to be "they're literally teenagers btw," "you're literally criticizing teenagers," "you could never accomplish what they have at 17" etc etc.
Yes some of them are teenagers, but they also made the choice to become public figures who release music to the public so yeah I do think the public has the right to say "I thought that song was bad." And good on them for being self-produced, but sometimes self-produced songs are still bad.
They're also teenagers, not children, and therefore self aware of themselves and what they do, so yes I think they can face criticism for their actions. Regardless of if they're 17 I am going to call an obvious blaccent a blaccent.
I also don't even think their fans inoculating them from criticism like this will help them grow as artists. If anything they do is okay because they're teenagers and any song they put is out is great because they're teenagers, there's no room to grow.