You might want to sort your double negatives. I do not think you wrote what you wanted to write.
Itch does not have an adult section. And you can't opt out of adult content. You will see adult content, even if you opted out. The only (!) thing the adult content option in your setting does is this: if you hit the browse and search, those games will not appear as results.
But visit a regular game, go to the developers page, you will see the adult games that developer has published. Click on a direct link to a game also works, though there will be a warning page in front. And also, you will see adult content if you select the adult tag. The setting is ignored for that. And a year ago they even had the adult tag in the tag selection list for account that did have opted out, so you could accidentally click. That has happened and they eventually "fixed" that. But not by making the setting work, but by removing the tags from the sfw list.
Oh, and publish a horror game and think it is inappropriate for 13 year olds, and now your account is barred from opting out of adult content.
There is much to fix in how the adult setting works.