Created attachment 142233 [details]
The yes/no dialog in question

SUMMARY
The 'Are you sure you want to open [multiple] items' when you try to open multiple things at once no longer responds to arrow-key input. Earlier, the left arrow key would select 'Yes', and you could press enter and the items would open. Now, the arrow key appears to change focus (?) to the 'Yes', but it doesn't actually select it and consequently when pressing enter the 'No' is entered.

STEPS TO REPRODUCE
1. Get to a directory with more than 5 items
2. Select all and press enter
3. The 'Are you sure you want to open (number you have selected) items' dialog opens up
4. Try to navigate to 'Yes' using the arrow key only.
5. Press enter

OBSERVED RESULT
'No' is the entered result

EXPECTED RESULT
'Yes' should be entered, and the items should open

SOFTWARE/OS VERSIONS
Operating System: KDE neon Testing Edition
KDE Plasma Version: 5.22.90
KDE Frameworks Version: 5.87.0
Qt Version: 5.15.3
Kernel Version: 5.11.0-37-generic (64-bit)
Graphics Platform: X11
Graphics Processor: Mesa Intel® HD Graphics 620

ADDITIONAL INFORMATION
-Clicking 'Yes' works just fine.
-Plasma 5.23 beta.
-Dolphin version is actually 21.08.2, but that isn't there in the version list in this bug for some reason.
-Attached screenshot of the dialog in question.