SUMMARY
Hi.
As for some limitation, my system doesn't work well with Xwayland, so I have had give preference in use X11 instead.
Now, I am using Neon Unstable with Plasma 6 Beta2.
The issue is, when using X11 with Plasma 6 Beta2, the Dolphin panels for Local and Preview just gone.
I need to press F9 and F11 in order to see it again.


STEPS TO REPRODUCE
1. Install Neon Unstable
2. Using X11
3. Open Dolphin
4. When minimize and restore the Dolphin window, Local and Preview panel both are gone
5. Press F9 and F11 make the panels appears again

OBSERVED RESULT
No Local and Preview panel in Dolphin, after minimize/restore window

EXPECTED RESULT
I expected the Dolphin keep Local and Preview panel visible, whatever using X11 or Wayland.

SOFTWARE/OS VERSIONS
Operating System: KDE neon Unstable Edition
KDE Plasma Version: 5.91.90
KDE Frameworks Version: 5.248.0
Qt Version: 6.6.1
Kernel Version: 6.5.0-14-generic (64-bit)
Graphics Platform: X11
Processors: 4 × AMD A12-9720P RADEON R7, 12 COMPUTE CORES 4C+8G
Memory: 15.1 GiB of RAM
Graphics Processor: AMD Radeon R7 Graphics
Manufacturer: Acer
Product Name: Aspire A515-41G
System Version: V1.09

ADDITIONAL INFORMATION
inxi 
CPU: quad core AMD A12-9720P RADEON R7 12 COMPUTE CORES 4C+8G (-MT MCP-)
speed/min/max: 1532/1400/2700 MHz Kernel: 6.5.0-14-generic x86_64 Up: 1h 21m
Mem: 4118.0/15438.5 MiB (26.7%) Storage: 931.51 GiB (22.6% used) Procs: 267
Shell: Bash inxi: 3.3.13