Users who are not signed in can go into Mature Content channels
Since I couldn't find a category for it in Support, I will put it as a bug/idea.
When you don't login into twitch you can simply enter names of "mature content" channels and browse freely.
I tested it on Smart TVs, phones, PCs and went to several known "mature content" (18+) channels and watched freely.
This means any kid can watch freely that content.
I recommend enforcing it that Mature Content requires Age + Mail verification.
Please do not allow streams containing mature content to be publicly viewed or displayed on your main page without a user logging in. Currently there is quite an abundance of mature content streams that appear on your main page on a regular basis including those that are viewed as sexual in nature and can be viewed by anyone without even logging into Twitch. This can be considered a serious violation of community guidelines as many underage children are being allowed access to the mature content that your site is displaying.