Things that you've encountered on people social media bios / personal website about pages that confuse or otherwise annoy you.
I'll go first:
when artists says they both "both nsfw and sfw" like as though they think it isn't normal for an artist to depict things that vary in sensitivity. Like just say your gallery is overall for 18+ audiences, that doesn't oblige you to make every piece 18+.
It'd be like if someone gave you a dish that is "both spicy and not spicy" because only the chili is contributing to it.
Also the concept of someone being an "nsfw/sfw artist" is strange in itself, but I get what it's trying to convey at least. It's useful to know what'll show up on your feed. That's why saying you're both is meaningless.
Many artists do specialize in one or the other, the label does make sense within the context.