"Karens" implies middle aged women.

This is not that.

This is a coordinated attack by organized conservative groups in order to drum up publicity and engagement, likely for an election that's coming up in your area. There might be a bond issue for the library that will be on the ballot that they want voted down.

Whatever the issue, they are trying to rile up the conservative base with a red herring about what's available at the library.

Instead of blaming this on unseen women, put the blame where it belongs - on the wider, organized conservative political action groups that are so well funded that they have the time and money to focus on random public libraries throughout the country