Attach (recommended) or Link to PDF file here:
[example.pdf](https://github.com/mozilla/pdf.js/files/6916129/example.pdf)

Configuration:
- Web browser and its version: Chrome, Firefox
- Operating system and its version: all
- PDF.js version: various versions, including 2.11.54
- Is a browser extension: no

Screenshot with visible textLayer:
![Screenshot from 2021-08-02 13-05-03](https://user-images.githubusercontent.com/6362989/127844878-f85e291f-2060-4028-be09-7835f32ccfaa.png)

Which means some letters at the beginning/end of text selection are missing when copying text.

t[226] = 352;
  t[227] = 353;
  t[228] = 381;
  t[229] = 382;
  t[233] = 221;
  t[234] = 253;
  t[252] = 263;
  t[253] = 268;
  t[254] = 269;
  t[258] = 258;
  t[260] = 260;
  t[261] = 261;
  t[265] = 280;
  t[266] = 281;
  t[267] = 282;
  t[268] = 283;
  t[269] = 313;
  t[275] = 323;
  t[276] = 324;
  t[278] = 328;
  t[283] = 344;
  t[284] = 345;
  t[285] = 346;
  t[286] = 347;
  t[292] = 367;
  t[295] = 377;
  t[296] = 378;
  t[298] = 380;
  t[305] = 963;
  t[306] = 964;