SUMMARY
When plugging in my laptop's charger, the Undo action gets triggered on text written in Kickoff or Krunner. This is particularly frustrating if one has a flaky charger, prone to disconnecting easily.
It doesn't seem to affect any other apps.

When I plug it in, the journal shows the following line:
kernel: asus_wmi: Unknown key code 0xcf

Recording the "Asus WMI hotkeys" event with libinput yields the following output:
  - evdev:
    - [  0,      0,   4,   4,      30] # EV_MSC / MSC_SCAN                 30 (obfuscated)
    - [  0,      0,   1, 240,       1] # EV_KEY / KEY_UNKNOWN               1
    - [  0,      0,   0,   0,       0] # ------------ SYN_REPORT (0) ---------- +0ms
  - evdev:
    - [  0,     18,   1, 240,       0] # EV_KEY / KEY_UNKNOWN               0
    - [  0,     18,   0,   0,       0] # ------------ SYN_REPORT (0) ---------- +0ms

Both unmapping the Undo action through the system settings and changing keyboard layout from pt_PT to en_US have no effect.

STEPS TO REPRODUCE
1. Write something in Kickoff and delete one character;
2. Plug in the charger.

OBSERVED RESULT
The deleted character reappears. If the charger is unplugged and plugged back in, the whole text gets deleted.
This is consistent with pressing Ctrl+Z twice.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 6.2.1
KDE Frameworks Version: 6.7.0
Qt Version: 6.8.0
Kernel Version: 6.11.4-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 4 × Intel® Core™ i7-7500U CPU @ 2.70GHz
Memory: 8.2 GB of RAM
Graphics Processor: Mesa Intel® HD Graphics 620
Manufacturer: ASUSTeK COMPUTER INC.
Product Name: X556URK
System Version: 1.0