SUMMARY
I don't use the split view often, but when I do I only enable it temporarily. Because of this, I see the left pane as the "fixed" pane and the right pane as the "temporary" pane. This is because the animation shows a new pane appearing from the right. I always get tripped up because I expect the Close button to close the "temporary" pane. Currently, the pane that actually gets closed is dependent on which pane is active.

STEPS TO REPRODUCE
1. Open a split view
2. Click the right-hand pane
3. Close the split view

4. Open a split view
5. Click the left-hand pane
6. Close the split view

OBSERVED RESULT
First the left-hand pane disappears, and then the right-hand pane disappears (depending on Dolphin's current settings).

EXPECTED RESULT
If a settings option such as "Turning off split view closes right-hand pane" existed, then I would expect the right-hand pane to always disappear.

SOFTWARE/OS VERSIONS
Operating System: openSUSE Tumbleweed 20230119
KDE Plasma Version: 5.26.5
KDE Frameworks Version: 5.102.0
Qt Version: 5.15.8
Kernel Version: 6.1.7-1-default (64-bit)
Graphics Platform: X11

ADDITIONAL INFORMATION