Rendering nested object in multipart/form-data request "try it out" shows JSON vs form UI fields

Q&A (please complete the following information)

• OS: macOS
• Browser: chrome
• Version: 95.0.4638.69
• Method of installation: non, using online version https://editor.swagger.io/
• Swagger-UI version: [e.g. 3.10.0]
• Swagger/OpenAPI version: OpenAPI 3.0.3

Example Swagger/OpenAPI definition:

openapi: 3.0.3
info:
    title: 'My API'
    version: 3.0.0
servers: []
paths:
    /api_app:
        post:
            operationId: apiAppCreate
            requestBody:
                content:
                    multipart/form-data:
                        schema:
                            $ref: '#/components/schemas/ApiAppCreateRequest'
            responses:
                '200':
                    description: 'success'
                    content:
                        application/json:
                            schema: {}
components:
    schemas:
        ApiAppCreateRequest:
            properties:
                oauth:
                  type: object
                  properties:
                      callback_url:
                          type: string
                          example: 'https://example.com/oauth'
                      scopes:
                          type: array
                          items:
                              type: string
                          example:
                              - basic_account_info
                              - request_signature
            type: object

Describe the bug you're encountering

When a component schema is defined that has another object nested inside of it, the UI shows JSON instead of form fields in the "try it out" page.

To reproduce...

Steps to reproduce the behavior:

1. Go to https://editor.swagger.io/
2. Paste the above example
3. Click on POST /api_app
4. Click "Try it out"
5. See JSON:

Expected behavior

I believe nested objects should be represented with UI fields like any other root-level field. For example, if I move callback_url and scopes into the top-level of ApiAppCreateRequest:

openapi: 3.0.3
info:
    title: 'My API'
    version: 3.0.0
servers: []
paths:
    /api_app:
        post:
            operationId: apiAppCreate
            requestBody:
                content:
                    multipart/form-data:
                        schema:
                            $ref: '#/components/schemas/ApiAppCreateRequest'
            responses:
                '200':
                    description: 'success'
                    content:
                        application/json:
                            schema: {}
components:
    schemas:
        ApiAppCreateRequest:
            properties:
              callback_url:
                  type: string
                  example: 'https://example.com/oauth'
              scopes:
                  type: array
                  items:
                      type: string
                  example:
                      - basic_account_info
                      - request_signature
            type: object

this is what I now see:

The problem is more obvious when you mix root-level properties with nested objects:

Reproduce the issue in Swagger UI's "Try it out" request-body form using the supplied OpenAPI 3.0.3 example. Inspect the multipart/form-data rendering path for nested object properties and compare it with the root-level case. Done means nested object fields render as form inputs rather than a JSON editor, while mixed root and nested properties remain usable.