[Bug 2125450] [NEW] Firefox loses characters when scanning barcodes with USB HID Keyboard on Ubuntu 22.04+ (works in 20.04)

[Alejandro Rodas]

Public bug reported:

When using a barcode scanner in USB PC Keyboard (HID) mode, Firefox randomly drops or misses digits if the scan is fast.
This issue appears in Ubuntu 22.04 and 24.04, but not in Ubuntu 20.04.

Steps to reproduce
- Install Ubuntu 22.04 or 24.04 (fresh installation).
- Install Firefox from Ubuntu repositories (apt install firefox).
- Connect a barcode scanner configured as USB PC Keyboard (HID).
- Open any webpage with a text input (for example a form or search field).
- Scan a long barcode (15+ digits) multiple times at normal speed.

Expected result
All digits from the barcode should appear exactly as scanned.

Actual result
Firefox randomly loses or skips some digits during the scan.
Other applications such as Gedit, Terminal, or Chrome/Chromium receive the complete code correctly.

Additional information
- Tested with Honeywell barcode scanners in USB PC Keyboard mode.
- Reproducible on multiple computers and different scanners.
- Happens on both X11 and Wayland sessions.
- Increasing the scanner's Intercharacter Delay to 50 ms or more avoids the problem.
- This issue does not occur on Ubuntu 20.04 with the same scanner and Firefox version.

System information
Ubuntu version: 24.04.2 LTS (also reproducible on 22.04.3)

** Affects: firefox (Ubuntu)
     Importance: Undecided
         Status: New

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Title:
  Firefox loses characters when scanning barcodes with USB HID Keyboard
  on Ubuntu 22.04+ (works in 20.04)

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