Just for the record, Airbnb Payments Terms of Service have been updated from today, March 25, 2019. (Regular T&Cs will be updated from Wednesday, March 27, and all users who joined on or before Jan 21, 2019 will have to agree to these in order to continue using the platform)
It's unclear at this point exactly how the changes in Payment Terms will affect users, but from today, a new contracting entity - Airbnb Payments Luxembourg SA - will be operational.
For all European Union residents, the contracting entity will now be either Airbnb Payments Luxembourg SA or Airbnb Payments UK Ltd for all transactions on and after March 25, 2019, "as notified to you at the time of checkout or by other appropriate means"
No further information is available at this time regarding which EU users will be paid by which entity (UK or Luxembourg), or why.