@moonspider a couple things:
traditional content warnings aren’t about offensiveness, but the fact that a topic might be upsetting for some people. Sometimes a topic is both (eg. homophobia) but bugs and medical needles are two frequently warned for things where i think it is fairly clear the warning is not any kind of moral/cultural judgement or indication of offensiveness
fedi in particular—especially pre-Musk buying twitter fedi—has a culture of using CWs for an even wider variety of things from including collapsing long posts or threads, spoiler warnings for shows, hiding the punchline of a joke, etc. You might argue this means the feature should be renamed but regardless the fact is there is very little association between using a CW and indicating something is distasteful or offensive
As for selfies in particular, its a curtesy towards people who are startled by unexpected eye contact, which is why often the CWs in question are phrases like “selfie, eye contact” or “selfie but no ec”
@moonspider eye contact might be the reason for warning, but that doesn’t mean its not helpful to know what the context its happening in is, right? like, saying its a selfie gives you a fairly clear idea of what you’ll get when you open the CW
consider that selfies, mugshots, photos of celebrities, and an artsy macro shot of someones eye could all be warned as “eye contact”—one might, for example, be fine with looking at selfies posted by your friends because you know them but not the other three!
@Satsuma makes sense but also convincing me to never post selfies or any photos if I can help it lol