The Hadozee were a race of flying ape aliens that first appeared in the original D&D books in 1982. The issue with the content arises from their backstory, as the Hadozee were kidnapped by a wizard who forcibly conducted experiments on them with the intent of selling them later for profit as soldiers.
Their backstory draws all sorts of comparisons to real historical events that involved forced experimentation on individuals against their will, such as the Tuskegee experiments as well as the horrors performed by Joseph Mengele at Birkenau. Several members of the D&D community flagged it as offensive in D&D forums and on social media. WotC acknowledged the issue in a post on the D&D website. "We wanted to acknowledge and own the inclusion of offensive material within our recent Spelljammer: Adventures in Space content," they wrote. "We failed you, our players and our fans, and we are truly sorry." WotC reassured its audience that they are continuing to take steps to "...work to better ensure a more inclusive game."
It is unclear what this situation means for licensed Spelljammer products, such as Beadle & Grimm's D&D Spelljammer: Adventures in Space - Platinum Edition, which is supposed to release in Q4 2022 (see "'D&D Spelljammer: Adventures in Space - Platinum Edition'").
[Note: This article was corrected at 1:38 p.m. CT, September 7 to clarify that content was removed, not the race. Apologies for the error. ed.]