Attach (recommended) or Link to PDF file here:

Configuration:
- Web browser and its version: Version 81.0.4044.138 (Official Build) (32-bit)
- Operating system and its version: Windows 10
- PDF.js version: latest
- Is a browser extension: no

Steps to reproduce the problem:

1. Open https://mozilla.github.io/pdf.js/web/viewer.html
2. Open the provided document
3. ctrl + F  and search for 'costs' .
4. Search for 'costs' - match NOT found.
5. Click the 'Download' and open the file in Adobe Reader, and search for costs - match is found.

What is the expected behavior? (add screenshot)
The word 'costs' to be returned by search

What went wrong? (add screenshot)
No results found

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):  https://mozilla.github.io/pdf.js/web/viewer.html
[2001_IESC_63_5_v6.pdf](https://github.com/mozilla/pdf.js/files/4644486/2001_IESC_63_5_v6.pdf)

PasswordException,
  PasswordResponses,
  PermissionFlag,
  StreamType,
} from "../../src/shared/util.js";
import {
  buildGetDocumentParams,
  DefaultFileReaderFactory,
  TEST_PDFS_PATH,
} from "./test_utils.js";
import {
  DefaultCanvasFactory,
  getDocument,
  PDFDataRangeTransport,
  PDFDocumentLoadingTask,
  PDFDocumentProxy,
  PDFPageProxy,
  PDFWorker,
  RenderTask,
} from "../../src/display/api.js";
import {
  RenderingCancelledException,
  StatTimer,
} from "../../src/display/display_utils.js";
import { AutoPrintRegExp } from "../../web/ui_utils.js";
import { GlobalImageCache } from "../../src/core/image_utils.js";
import { GlobalWorkerOptions } from "../../src/display/worker_options.js";
import { isNodeJS } from "../../src/shared/is_node.js";
import { Metadata } from "../../src/display/metadata.js";
describe("api", function () {