The point is, that you are not supposed to be able to browse for adult content, without having an account.
Selecting tag adult in browse should not change this. It suddenly ignores, wether you are logged in or not, and if you are logged in, wether or not you have opted in for adult stuff.
In other words, the itch browse feature should under no circumstances provide users with the direct links needed to access adult content. Except if they are logged in and opted in.