According to the Summary of Decisions, Editorial Meeting 5, May 13, 2022, the Library of Congress vocabulary editors decided not to approve the LCGFT proposal for Speculative fiction.
The reasoning: Sources describing this genre convey a lack of consensus on the meaning of the term. The Oxford Research Encyclopedia of Literature provides several definitions for speculative fiction ranging from a specific subgenre of science fiction to a super category encompassing all fiction that departs from "reality". Because the usage is still in flux for this term and consensus has not been reached on its meaning, the term was not approved, but may be resubmitted at a future time when the boundaries of the genre are more concrete.
I very much enjoy that the reasoning matches the term. And while I'm speaking of science fiction (or, rather, they're speaking of science fiction), we went to the movie Everything Everywhere All at Once last night and it's quite amusing and strangely optimistic. It is very nice to be in Cambridge with the Kendall Square Cinema just down the street. It was, however, one of my first visits there where I wasn't ready to rush to each of the previewed movies.