This is very confusing as seen in #12974 or #12906. My suggestion would be "legacy."
var evaluatorOptions = {
        maxImageSize: data.maxImageSize,
        disableFontFace: data.disableFontFace,
        ignoreErrors: data.ignoreErrors,
        isEvalSupported: data.isEvalSupported,
        fontExtraProperties: data.fontExtraProperties,
      };
      getPdfManager(data, evaluatorOptions)
        .then(function (newPdfManager) {
          if (terminated) {
            
            
            newPdfManager.terminate(
              new AbortException("Worker was terminated.")
            );
            throw new Error("Worker was terminated");
          }
          pdfManager = newPdfManager;
          pdfManager.onLoadedStream().then(function (stream) {
            handler.send("DataLoaded", { length: stream.bytes.byteLength });
          });
        })
        .then(pdfManagerReady, onFailure);
    }
    handler.on("GetPage", function wphSetupGetPage(data) {
      return pdfManager.getPage(data.pageIndex).then(function (page) {
        return Promise.all([
          pdfManager.ensure(page, "rotate"),
          pdfManager.ensure(page, "ref"),
          pdfManager.ensure(page, "userUnit"),