We could use:
https://github.com/mozilla/pdf.js/blob/c3d08580627471432a6ad0b2fdb948df64126afa/src/display/api.js#L929

and look at bit 4.

The following pdf:
https://orimi.com/pdf-test.pdf
is not editable in neither Acrobat nor Edge nor Foxit and nor Okular.
let newScale = this._currentScale;
    do {
      newScale = (newScale * DEFAULT_SCALE_DELTA).toFixed(2);
      newScale = Math.ceil(newScale * 10) / 10;
      newScale = Math.min(MAX_SCALE, newScale);
    } while (--steps > 0 && newScale < MAX_SCALE);
    this.currentScaleValue = newScale;
  }
  /**
   * Decrease the current zoom level one, or more, times.
   * @param {number} [steps] - Defaults to zooming once.
   */
  decreaseScale(steps = 1) {
    let newScale = this._currentScale;
    do {
      newScale = (newScale / DEFAULT_SCALE_DELTA).toFixed(2);
      newScale = Math.floor(newScale * 10) / 10;
      newScale = Math.max(MIN_SCALE, newScale);
    } while (--steps > 0 && newScale > MIN_SCALE);
    this.currentScaleValue = newScale;
  }
  updateContainerHeightCss() {
    const height = this.container.clientHeight;
    if (height !== this.#previousContainerHeight) {
      this.#previousContainerHeight = height;
      docStyle.setProperty("--viewer-container-height", `${height}px`);
    }
  }
  get annotationEditorMode() {