This kind of thing happens commonly with language development over time. If a word or phrase picks up a strong connotation, then the word or phrase stops being used generically. This used to happen so slowly that nobody really noticed it happening to individual words or phrases, I think.
As an example, starting a fire could be called “firing”. If you say you’re going to “fire the stove”, that isn’t typically said, but everyone would know what you meant. If you call your friend group a “squad”, again, this isn’t typically said, but everyone would know what you meant.
If your friend group goes camping and works together to light a fire, you could say that you’re part of a “firing squad”. But, that already has such a strong connotation that it would be confusing and you would have to constantly explain what you actually mean because “firing squad” as a phrase is already taken.
That is of course a synthetic example but I think it illustrates the point. When we say “banned books”, that has a certain connotation. If what we mean is more like “curated books”, because they aren’t actually banned for sale anywhere, even at the local level, then saying “banned books” is confusing in the same way and it carries an undue emotional charge from the typical usage of that phrase.
If that undue emotional charge seems to be getting weaponized, then using it and acting innocent about it is going to ruffle some feathers.