Very odd.
I can’t explain this.
The uk Amazon website makes no mention of zigbee cabability
Echo Dot (5th generation, 2022 release) | Big vibrant sound Wi-Fi and Bluetooth smart speaker with Alexa | Deep Sea Blue
Nor does this review
Is it possible uk version doesn’t have zigbee but USA version does?
This detailed review also says only the larger echo devices support zigbee so something is not adding up here. 
