Itch.io is a site primarily for adults.
“Not Safe for Work” is an extremely vague phrase that shouldn’t have ever become common sites, because it’s heavily dependent on experiences that often conflict. Some workplaces display nudity or depict sexual acts. Some places work with blood and mangled bodies. There’s lots of crossover, like at hospitals and art museums.
It’s too confusing. Maybe Itch.io will move away from the “NSFW” terminology in all the change it’s going through.