SUMMARY
The field "Allow unlocking without password for:" erroneously transforms its input when the input has more than three digits and when the field loses focus. Incrementing the number beyond 999 with the mouse while keyboard focus is elsewhere works.

I have not checked whether that value is actually honoured as the timeout value.

STEPS TO REPRODUCE and OBSERVED RESULTS
It seems there are two opinions on how to parse the input that can be triggered distinctly:

a1. enter a four digit number;
a2. hit enter  =>  the input is formatted according to the locale by inserting a blank or a comma (tested with en_GB and de_AT) and the cursor is moved behind "seconds";
a3. hit enter  =>  the three rightmost digits are truncated.

b1. enter a four digit number;
b2. move focus elsewhere  =>   the input is formatted according to the locale and this setting could be applied at this point;
b3. move focus back to the field;
b4. move focus elsewhere  =>   the three rightmost digits are truncated.

c1. enter a four digit number;
c2. move focus elsewhere  =>  the input is formatted according to the locale;
c3. increment the timeout value with the mouse, without focusing the field  =>  the value is incremented correctly.

This may be a different bug:
d1. enter a four digit number;
d2. move focus elsewhere  =>  the input is formatted according to the locale;
d3. move focus back to the field;
d4. remove the thousands separator;
d5. move focus elsewhere  =>  the input is NOT formatted according to the locale.


EXPECTED RESULT
Four digit numbers not having their three rightmost digits truncated.


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 6.6.44-1-MANJARO (64-bit)
KDE Plasma Version: 6.0.5
KDE Frameworks Version: 6.4.0
Qt Version: 6.7.2
Wayland