In file https://github.com/mozilla/pdf.js/files/5249872/product1.pdf, the fifth text widget has a default appearance using font F1 and this one is neither in DR nor in AcroForm but in AP::N::Resources.
const dict = xref.fetchIfRef(ref);
    if (!isDict(dict)) {
      return undefined;
    }
    const id = isRef(ref) ? ref.toString() : `annot_${idFactory.createObjId()}`;
    
    let subtype = dict.get("Subtype");
    subtype = isName(subtype) ? subtype.name : null;
    
    const parameters = {
      xref,
      ref,
      dict,
      subtype,
      id,
      pdfManager,
      acroForm: acroForm instanceof Dict ? acroForm : Dict.empty,
    };
    switch (subtype) {
      case "Link":
        return new LinkAnnotation(parameters);
      case "Text":
        return new TextAnnotation(parameters);
      case "Widget":
        let fieldType = getInheritableProperty({ dict, key: "FT" });
        fieldType = isName(fieldType) ? fieldType.name : null;
        switch (fieldType) {