It's only US users right now. Here's a more detailed announcement: https://www.airbnb.com/resources/hosting-homes/a/a-new-way-w...
Whatever good intention might be behind this, it's really off-putting to me. They send your photo and name to a third party who is tasked with evaluating those to determine your race.
"will look at these photos and first names and indicate their perceptions—or, what race they think the information we shared suggests. They’ll share these perceptions with a specialized team at Airbnb exclusively for anti-discrimination work"
Presumably that'll be correlated to booking data to identify rejections. I can't think of any other use case.
Gotta say, if someone truly doesn't want me to stay somewhere because of my race, I'll take that rejection rather than force myself into a shitty situation.