BluFi BLE Service UUID in violation of BLE standard?

[claudeHasler]

According to this documentation:
https://docs.espressif.com/projects/esp ... blufi.html

a device supporting BluFi advertises the 16 bit Service UUID 0xFFFF.

The assigned numbers document (https://www.bluetooth.com/specifications/an/) makes no mention of such a service.

As far as I understand it, the 16 bit UUIDs are reserved for the services defined by the BLE standard, and only 128-bit service UUIDs are for custom services.

Is espressif in violation of the BLE standard / BLE conventions? Or how can this be explained?

Regards

Claude