This was a manufactured problem used as an excuse to remove the books.

Basically a YouTuber karen has made it their personal mission to remove the books because she liked every about plantation history except acknowledging that "brutal enslavement" bit, so she makes a video about it and sends the video along with threats of contacting the legislature about the books to some low level party involved with the texas commission.

The spineless weasel watches the video, agrees with it, and then escalates the threat to the "historical society" leadership, which is all directly appointed by the executive branch of texas. They tell the weasel that they prefer to talk face to face, i.e "no records you idiot," then suddenly 20+ books about slavery disappear from plantation gift shops, under the premise that a book must "be directly applicable to texas history." Of course, some of those books about slavery are directly applicable, but they are still gone. Southern Cookbooks, books about flowers, things that are not applicable to texas history stuck around no problem.

This was a ginned up controversy, and all the parties involved worked together to remove books about slavery from slave plantations because they all wanted them gone.

This article has a deeper dive into what happened.