SUMMARY
Pressing Backspace in Kicker if an item is selected will create a "missing glyph" box character. 
See:https://docs.microsoft.com/en-us/typography/opentype/spec/recom#glyph-0-the-notdef-glyph

STEPS TO REPRODUCE
1. launch kicker
2. press up arrow or hover mouse to select any entry (there should no longer be an I beam in search field)
3. press backspace

OBSERVED RESULT
A missing glyph character is inserted instead of deleting.

EXPECTED RESULT
Backspace will delete a character.

SOFTWARE/OS VERSIONS
This bug occurs in both my systems:
(Virtualbox)
Kde Neon Unstable
KDE Plasma Version: 5.18.80
KDE Frameworks Version: 5.70.0
Qt Version: 5.14.2

(Hardware Install)
Manjaro 20.0.1
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.70.0
Qt Version: 5.14.2
Kernel Version: 5.6.12-1-MANJARO
OS Type: 64-bit


ADDITIONAL INFORMATION
When repeating these steps and pressing the delete key instead, this character is produced:
Pressing backspace again will delete characters as usual, until there is no more text. After that, backspace will create a missing glyph symbol again (delete will also create its own character).