example code how to format query for retrieving a month from the GraphQL api

Get-TibberMonth.ps1

function Get-TibberMonth {
  <#
        .DESCRIPTION
        gets tibber usage for a month, will automatically turn any date into the first day of the month
        and will calculate the amount of hours for that month
        .PARAMETER Startdate
        startdate
        if no enddate is given it will take day 1 of the month in startdate and +1 month
        .PARAMETER Enddate
        enddate
        .PARAMETER Export
        exportpath for the json file
        .PARAMETER Passthru
        will return the data
        .EXAMPLE
        $data = Get-TibberMonth -StartDate 2023-10-10 -Export .\test.json -Passthru
        .EXAMPLE
        $tibber = Get-TibberMonth -StartDate 2023-03-01 -EndDate 2023-05-30
    #>
  [CmdletBinding()]
  param(
    [Datetime]
    $StartDate = (Get-Date).AddMonths(-1),
    [Datetime]
    $EndDate,
    [String]
    $Export,
    [Switch]
    $Passthru,
    [String]
    $Token,
    [String]
    $UserAgent = 'powershell'
  )
  Import-Module PSTibber
  if ($Export -and (Test-Path -LiteralPath $Export)) {
    throw "File $Export already exists"
  }
  $tibber = @{
    PersonalAccessToken = $Token
    UserAgent           = $userAgent
    ErrorAction         = 'Stop'
  }
  if (-Not $EndDate) {
    # if no enddate it will just return 1 month from the first day of that month.
    $date = Get-Date $StartDate -Day 1 -Hour 0 -Minute 0 -Second 0
    [int]$hours = ($date.AddMonths(1) - $date).TotalHours
  }
  else {
    $date = $StartDate
    [int]$hours = ($EndDate - $StartDate).TotalHours
  }
  $DateString = Get-Date -Date $date -Format s
  $DateByte = [System.Text.Encoding]::UTF8.GetBytes($DateString)
  $base64DateTime = [System.Convert]::ToBase64String($DateByte)
  Write-Verbose "S: $StartDate, E: $Enddate, D: $date, DS: $datestring, H: $hours"
  $tibber.Query = @"
{
  viewer {
    homes {
      consumption(resolution: HOURLY, after: `"$base64DateTime`", first: $hours) {
        nodes {
          from
          cost
          unitPrice
          unitPriceVAT
          consumption
          consumptionUnit
          currency
        }
      }
      production(resolution: HOURLY, after: `"$base64DateTime`", first: $hours) {
        nodes {
          from
          profit
          unitPrice
          unitPriceVAT
          production
          productionUnit
          currency
        }
      }
    }
  }
}
"@
  $data = Invoke-TibberQuery @tibber
  $nicerData = [PSCustomObject]@{
    Consumption = $data.viewer.homes.consumption.nodes
    Production  = $data.viewer.homes.production.nodes
  }
  if ($Export) {
    $nicerData | ConvertTo-Json -Depth 10 | Set-Content -Path $Export
    if ($Passthru) {
      $nicerData
    }
  }
  else {
    $nicerData
  }
}