For the uninitiated, generally NSFW is for sexual contents and NSFL is for gory contents. People may want to see one but not see the other at any time for any reason. I have seen this feature requested over the years in Reddit but it never happens. Maybe now some instance can finally implement it?
Another great one would be for phobias, being able to filter out images of a snake for example if you hate them. Sometimes the title filtering can do that but that doesn’t work when someone titles their picture “look at this cute little guy”
That’s a good idea. The client could let the user select their phobia from this list of all phobias from Wikipedia with a description and then filter for the tags matching the description.