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.
this.#size = newSize;
    const buf = this.#buf;
    if (idsToKeep) {
      const ii = buf.size;
      let i = 1;
      for (const view of buf) {
        if (idsToKeep.has(view.id)) {
          buf.delete(view); 
          buf.add(view);
        }
        if (++i > ii) {
          break;
        }
      }
    }
    while (buf.size > this.#size) {
      this.#destroyFirstView();
    }
  }
  has(view) {
    return this.#buf.has(view);
  }
  [Symbol.iterator]() {
    return this.#buf.keys();
  }
  #destroyFirstView() {