Again, it's something your fandom doesn't talk about; or if it is brought up, people either deny, downplay, or think it isn't a problem.
I'm gonna guess the usual: racism, misogyny, fanservice, lolis, story quality, character quality, queerphobia (or fetishing of), ableism, facism, etc.
There are certain fandoms or pieces of media everyone knows for a specific problem or another. (i.e. mha, aot, tadc, etc.)
I know you're supposed to name what you're talking about, but feel free to not if you don't want to get hate because I understand completely.
Feel free to also name positive things you think should be talked about more! What's something about your fav media that wish got more attention?