Yeah people need to realize you can acrually "get away with" a lot, imagewise. It's the keywords that will kill you.
You need to understand what people search for. If you put Harry and Potter on different lines, of course it will still come up when someone searches for Harry Potter. You will kill it for a while, but that is what the lawyers and IP folks are also searching for. Once they find it you are done.
I wouldn't recommend blatant viilations in images/designs either, but there are, shall we say, peripheral references to trademarked movies, songs, and games, that you can make which will still be found by potential customers but not as obvious to a search run by a lawyer or bot.
And the older the IP, the more you can get away with. Think 1980s horror movies that have cult followings, songs by bands that do not exist anymore or have split up, dead, etc. Plenty of potential customers but not such a liability that they have entire law firms on staff patrolling this stuff.
I know someone on here is going to tell me I am wrong or playing with fire, but whatever. I am tier 4k and selling since 2015. I have never been suspended and am not greedy or spamming Fortnite or Harry Potter shirts either. There is a delicate balance. If you don't believe me that's fine. Just trying to give some perspective. Not everything is "Keep Calm and X On" or "I love my Dachsund" shit. There is gray area that has been safe for quite a while.