Likely they're mostly photographers. Airbnb hires a lot of professional photographers to take listing photos. Here's an example job posting: https://careers.airbnb.com/contractors/1404981/
But that posting is "freelance contractor" photographer which means they are not employees. Is AirBnb/LinkedIn counting non-employees in that ~3365 Arts & Design headcount?
Probably? I think it's self-reported. If I was mostly working for Airbnb as a photographer, I might put them as my employer on LinkedIn, freelance or no.