[Bug] Wrong area fill color when using group_by option

[HeuristicPerson]

Checklist

• I updated the card to the latest version available
• I cleared the cache of my browser
• I verified that I'm really running the lastest version in my browser console
• I checked if there is another issue opened with the same problem

Describe the bug
When using the group_by option the area is not filled with the proper gradient colors.

Version of the card
Version: v2.0.4

To Reproduce
This is the configuration I used:

type: custom:apexcharts-card
experimental:
  color_threshold: true
header:
  show: true
  title: Temperature
  show_states: true
  colorize_states: true
graph_span: 7d
yaxis:
  - min: 15
    max: 25
series:
  - entity: sensor.ht_sensor_3_xiaomi_lywsd03mmc_temperature
    type: area
    name: 6h avg
    color_threshold:
      - value: 23
        color: '#ff4b00'
      - value: 0
        color: '#4040ff'
      - value: 18
        color: '#4040ff'
      - value: 19
        color: '#bc8bbc'
      - value: 20
        color: '#ffbf00'
      - value: 21
        color: '#ffbf00'
      - value: 22
        color: '#ff9400'
    fill_raw: last
    group_by:
      duration: 6h
      func: avg
    stroke_width: 3
  - entity: sensor.ht_sensor_3_xiaomi_lywsd03mmc_temperature
    color: '#606060'
    name: instant
    fill_raw: last
    stroke_width: 1
    show:
      extremas: max

Screenshots
Wrong colors

Good colors

Expected behavior
When group_by option is used to time average the results, the gradient colors should adjust to the ones defined.

Desktop (please complete the following information):

• Browser Firefox / Chromium
• Version 124.0.1 / 123.0.6312.58

Additional context
Add any other context about the problem here.