SUMMARY

On Kubuntu 25.10, when attempting to add a new Keyboard Layout, found two issues that were not present in previous versions (like 25.04). Also reproduced that in Fedora 42 that was upgraded to Plasma 6.4.5.

1. The one with the bigger impact is that I was unable to add a Bulgarian Phonetic. Only one variant was listed in the list on the right, when they should be 4.
2. The second issue (a minor one in itself, but maybe also is a symptom of a bigger problem) is that the list with the languages on the left is sorted in a descending order.

STEPS TO REPRODUCE
1. Open Keyboard setting.
2. Enable layouts
3. Click button "Add..."
4. Type "bul" in the filter.

OBSERVED RESULT

Only 1 variant for Bulgarian listed.

EXPECTED RESULT

There should be 4 variants for Bulgarian.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 
KDE Plasma Version: 6.4.5
KDE Frameworks Version: 6.17.0
Qt Version: 6.9.2

ADDITIONAL INFORMATION

I also tested this: Close and reopen the Keyboard settings dialog. Add new layout. In the list I select "Bulgarian" w/o entering a filter. Then there are 4 variants (as expected). Then I enter "bul" and select "Bulgarian" again - there's only 1. Then I enter just "bu" - there is none. Same with "b".