Config structure change after upgrading Field Group to 8.x-3.3

Problem/Motivation

Hi,

I am porting Ui Patterns from Github to Drupal.org and enabling automated testing on Drupal.org, It catched a regression.

After some investigations, it is related to a change in how the config is stored by Field Group.

I am still doing investigations to isolate exactly from where this is coming from and to provide examples before/after.

8.x-2.2:

third_party_settings:
  field_group:
    group_aaaa:
      children:
        - body
      label: aaaa
      parent_name: ''
      region: content
      weight: 2
      format_type: pattern_formatter
      format_settings:
        pattern: metadata
        pattern_mapping:
          'fields:body':
            destination: field_1
            weight: 0
            plugin: fields
            source: body
        show_empty_fields: 0
        pattern_variant: first

8.x-3.3:

third_party_settings:
  field_group:
    group_aaaa:
      children:
        - body
      label: aaaa
      parent_name: ''
      region: content
      weight: 2
      format_type: pattern_formatter
      format_settings:
        pattern: metadata
        variants:
          metadata: first
        pattern_mapping:
          metadata:
            settings:
              'fields:body':
                destination: field_1
                weight: '0'
        show_empty_fields: 0

Steps to reproduce

Configure a field group to be rendered as a pattern.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes