The issue affecting Duffel-managed bookings with EasyJet and United has been resolved.
Due to ongoing system outages affecting various airlines at the moment, users may experience a higher number of booking failures than expected for both EasyJet and United, however the specific issue affecting Duffel Managed content has been resolved.
Duffel are tracking these external issues, and advise users to subscribe to the following incident to track further developments regarding airline system outages: https://www.duffelstatus.com/incidents/01J3523BRNVRQ3VCKXEKACHSY7