SUMMARY
Selecting multiple images, then opening the containing folder, use to open a single dialog window showing the selected images highlighted. Now it opens multiple dialog windows each window showing just one of the selected images highlighted. This makes it impossible to do things like renaming the group of selected files using the auto-incrementing file names feature.

STEPS TO REPRODUCE
1. Open Gwenview in a file directory containing multiple image files.
2. Select a number of images to be displayed all at once.
3. Right click on  any image shown, and select "Open Containing Folder"

OBSERVED RESULT
Multiple dialog windows are created,  each showing the containing folder, but with only one file highlighted from the set of selected files.

EXPECTED RESULT
Only one dialog window should be created and opened, showing the files in the containing folder, and with all selected files highlighted. This allows one to treat all of the selected files at once, such as renaming them. This is the way Gwenview has always worked in the past.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

Operating System: openSUSE Leap 15.4
KDE Plasma Version: 5.24.4
KDE Frameworks Version: 5.90.0
Qt Version: 5.15.2
Kernel Version: 5.14.21-150400.24.88-default (64-bit)
Graphics Platform: X11
Processors: 4 × Intel® Core™ i5-6500 CPU @ 3.20GHz
Memory: 15.5 GiB of RAM
Graphics Processor: Mesa DRI Intel® HD Graphics 530

ADDITIONAL INFORMATION

I believe this change of behavior occurred after a set of updates were applied to my system. I have no idea however of what was updated or when the changes were applied.