Uuuh honestly I never tag profanity as mature, in my opinion "naughty words" are super tame compared to the themes of my comic, and I'm really only saving those tags for nudity and really upsetting visuals. Like, I'm in the middle of drawing a scene right now where one of my MCs is cussing up a storm, and I don't plan on tagging it. Lol
My mindset is, if cussing of all things is going to be what makes a reader upset, then they shouldn't be reading my comic. I don't know how it is for you though, if your work is PG-13 or under then maybe use the tag for hard profanity, but if it is for an older crowd than I don't see the issue... although I'm not quite sure how it is for novels. I got uncomfortable visuals to take away from the fact that one of my characters has a sailors mouth, but you can't get that distraction with writing.