First Batch of Facebook Oversight Board Decisions Has Been Released

There are five, and you can read English-language summaries linked to from this page. Four of the five decisions reverse Facebook's decisions to remove content, and thus take a relatively speech-protective provision, though (unsurprisingly) not always as speech-protective a position as U.S. First Amendment law would apply to governmental restrictions on speech. The one decision that the panel upheld had to do with the use of an ethnic slur against Azerbaijanis in the Armenian-Azerbaijani conflict:

The post used the term "тазики" ("taziks") to describe Azerbaijanis. While this can be translated literally from Russian as "wash bowl," it can also be understood as wordplay on the Russian word "азики" ("aziks"), a derogatory term for Azerbaijanis which features on Facebook's internal list of slur terms. Independent linguistic analysis commissioned on behalf of the Board confirms Facebook's understanding of "тазики" as a dehumanizing slur attacking national origin.

It's possible that the nipple decision, by the way, would be actually more protective than First Amendment law would be as to governmental restrictions on speech on some kinds of government property. First Amendment law allows reasonable, viewpoint-neutral restrictions in such government-as-proprietor situations (as opposed to general bans on speech even on private property, with the private property owner's permission, imposed by the government as sovereign). A categorical ban on depictions of the female nipple in a limited public forum would likely be upheld under such a standard.