Flex Form Field is inaccessible after the 13.4.2 update

[tgrigoryan234]

Describe the bug After the minor update, the Flex Form fields are no longer accessible. It is empty.

To Reproduce Steps to reproduce the behavior:

 fields:
  - identifier: my_flexform
    type: FlexForm
    fields:
      - type: Sheet
        identifier: sheet1
        label: Sheet 1
        fields:
          - identifier: section1
            type: Section
            label: Section 1
            container:
              - identifier: container1
                label: Container 1
                fields:
                  - identifier: container_field
                    type: Text
              - identifier: container2
                label: Container 2
                fields:
                  - identifier: container_field2
                    type: Textarea

Screenshots

TYPO3 Version 13.4.2