From Wikipedia- The Voynich manuscript is an illustrated codex, hand-written in an unknown script referred to as Voynichese.[18] The vellum on which it is written has been carbon-dated to the early 15th century (1404–1438). Stylistic analysis has indicated the manuscript may have been composed in Italy during the Italian Renaissance.[1][2] While the origins, authorship, and purpose of the manuscript are still debated, hypotheses range from a script for a natural language or constructed language, an unread code, cypher, or other form of cryptography, or perhaps a hoax, reference work (i.e. folkloric index or compendium), or work of fiction (e.g. science fantasy or mythopoeia, metafiction, speculative fiction) currently lacking the translation(s) and context needed to both properly entertain or eliminate any of these possibilities.
Lisa Fagin Davis has an interesting 62 tweet long analysis of the manuscript, viewable here: https://threadreaderapp.com/thread/1557092705485967360.html
There’s also an article in the most recent Atlantic.