Looking to try understand this template error

Hey everyone,
I’m getting an error in visual studio code for my template which is used as part of a delayed notifications solution to hold notifications for me whilst in a do not disturb state and it still works and historically has since I first implemented it but now I’m getting the following error:

“String does not match the pattern of “LEGACY_SYNTAX^”.yaml-schema: http://schemas.home-assistant.io/integration-template

I’ve tried going to this link but it doesn’t appear to exist. Is this a visual studio code error or have templates changed the way they’re setup?

Here’s the template:

- trigger:
    - platform: event
      event_type:
        - message_create
        - message_delete
        - message_delete_all
  sensor:
    - name: Delayed Notifications
      unique_id: delayed_notifications_sensor
      state: "{{ now().timestamp() | timestamp_custom() }}"
      attributes:
        messages: >
          {% set msgs = this.attributes.get('messages', []) %}
          {% if trigger.event.event_type == 'message_create' %}
            {% set new = [{
                "id": trigger.event.data.id | default('TS' ~ now().timestamp()),
                "title": trigger.event.data.title | default(''),
                "message": trigger.event.data.message | default(''),
                "time": now().isoformat() }] %}
            {{ (msgs + new) | unique(attribute='id') | list }}
          {% elif trigger.event.event_type == 'message_delete' %}
            {% if trigger.event.data.id is defined %}
              {% set msgs = msgs | rejectattr('id', 'eq', trigger.event.data.id) | list %}
            {% elif trigger.event.data.index is defined and trigger.event.data.index | is_number %}
              {% set t = trigger.event.data.index | int(0) - 1 %}
              {% if 0 <= t < msgs|count %}
                {% set msgs = msgs | rejectattr('id', 'eq', msgs[t].id) | list %}
              {% endif %}
            {% endif %}
            {{ msgs }}
          {% else %}
            {{ [] }}
          {% endif %}

Change:

- trigger:
    - platform: event

to

- trigger:
    - trigger: event