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)

state,
  matchesPerPage,
  selectedMatch,
  pageMatches = null,
  pageMatchesLength = null,
}) {
  return new Promise(function (resolve) {
    const eventState = Object.assign(
      Object.create(null),
      {
        source: this,
        type: "",
        query: null,
        caseSensitive: false,
        entireWord: false,
        phraseSearch: true,
        findPrevious: false,
      },
      state
    );
    eventBus.dispatch("find", eventState);