Using the latest version (v1.11.1-0.20220727161132-874b0a16ac55)
I have a schema like

 x:
      allOf:
      - $ref: '#/components/schemas/y-base'
      properties:
        a:
          ....
        b:
          $ref: '#/components/schemas/b'
      type: object

I get code like:

// X defines model for x.
type X struct {
	// Embedded struct due to allOf(#/components/schemas/y-base)
	YBase `yaml:",inline"`
}

if the old-merge-schemas: true is true, and

// X defines model for x.
type X YBase

when its false, the other properties all ignored