SUMMARY
When working with two screens (laptop + external monitor), and the main display is external monitor,
after reboot, widgets positions are placed as the two monitors was only one (looks like it sees the position calculating the total area of the two displays, but I'm guessing).

STEPS TO REPRODUCE
1. Place an widget in the desktop (external monitor)
2. Reboot

OBSERVED RESULT
The widget was miss placed.

EXPECTED RESULT
The widget to be placed where I've set to be.

SOFTWARE/OS VERSIONS
Operating System: KDE neon 5.24
KDE Plasma Version: 5.24.3
KDE Frameworks Version: 5.91.0
Qt Version: 5.15.3
Kernel Version: 5.13.0-35-generic (64-bit)
Graphics Platform: X11
Processors: 8 × 11th Gen Intel® Core™ i7-1165G7 @ 2.80GHz
Memory: 31.1 GiB of RAM
Graphics Processor: NVIDIA GeForce MX350/PCIe/SSE2

ADDITIONAL INFORMATION
Look at the screenshots