Netatmo integration suddenly failed to set up

Solution found here:
https://community.home-assistant.io/t/problem-with-netatmo-bticino-integration-error-setting-up-entry-home-assistant-cloud-for-netatmo/514764/3

After an update, all the devices weren’t assigned to a room: assigning a room to them and reloading the integration from HA made everything work again.