I think there might be an issue with update frequency associated with using timestamp as the trigger. Can you try changing the configuration.yaml to the following:
rest_command:
my_request:
url: https://readings.powerpal.net/api/v1/meter_reading/<device-id>
method: POST
headers:
authorization: "authorization key"
accept: ""
payload: >-
[ {"cost":{{ states.sensor.powerpal_cost_json.state }},"is_peak": false, "pulses":{{ states.sensor.powerpal_pulses_json.state }}, "timestamp": {{ as_timestamp(now(),0) | int(0) }} , "watt_hours": {{ states.sensor.powerpal_watt_hours_json.state}} } ]
content_type: 'application/json'
verify_ssl: true
And automation.yaml:
alias: Powerpal Cloud Upload
description: ""
trigger:
- platform: time_pattern
minutes: /1
condition: []
action:
- service: rest_command.my_request
data: {}
mode: single