Only a 500 as a response

I'm trying to read the current temperature from my thermometer:

curl -i -X POST \
--header 'Govee-API-Key: <my api key>' \
--header 'Content-Type: applications/json' \
-d "{\"requestId\": \"$(uuidgen)\", \"payload\": {\"sku\": \"H5103\", \"device\": \"08:21:CB:39:32:34:50:23\"}}" \
https://openapi.api.govee.com/router/api/v1/device/state

The response is just a sad:

HTTP/2 500
date: Wed, 20 Mar 2024 08:39:08 GMT
content-length: 0

Any idea what I did wrong?