before angular 14, we open with 100% or 100vw, dialog will be fullscreen.

{
  width: '100%',
  height: '100%',
  maxWidth: '100vw',
  hasBackdrop: false,
  panelClass: 'wizard-dialog',
}

currently i using angular 17. the same configuration. the dialog contained padding even we open with 100% enter image description here

Add css :

.cdk-overlay-container .mat-mdc-dialog-container{ padding: 0px !important;}