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.
constructor() {
    throw new Error("Cannot initialize AppOptions.");
  }
  static get(name) {
    const userOption = userOptions[name];
    if (userOption !== undefined) {
      return userOption;
    }
    const defaultOption = defaultOptions[name];
    if (defaultOption !== undefined) {
      return compatibilityParams[name] ?? defaultOption.value;
    }
    return undefined;
  }
  static getAll(kind = null) {