Maximized window goes under panel

I use Lenovo ThinkPad 14s
display settings:

Summary
Device-1: AMD Renoir vendor: Lenovo driver: amdgpu v: kernel bus ID: 06:00.0 
  chip ID: 1002:1636 
  Device-2: IMC Networks Integrated Camera type: USB driver: uvcvideo 
  bus ID: 2-2:2 chip ID: 13d3:5405 serial: <filter> 
  Display: x11 server: X.Org 1.20.10 compositor: kwin_x11 driver: 
  loaded: amdgpu,ati unloaded: modesetting alternate: fbdev,vesa 
  display ID: :0 screens: 1 
  Screen-1: 0 s-res: 1920x1080 s-dpi: 96 s-size: 506x285mm (19.9x11.2") 
  s-diag: 581mm (22.9") 
  Monitor-1: eDP res: 1920x1080 hz: 60 dpi: 158 size: 309x174mm (12.2x6.9") 
  diag: 355mm (14") 
  OpenGL: renderer: AMD RENOIR (DRM 3.39.0 5.9.16-1-MANJARO LLVM 11.0.1) 

Moved panel to the right side of the screen.
Set panel “Always visible” and it works until you shutdown or restart device.
Afterwords maximized window goes under the panel and you have to manually toggle “Always visible” in order to have proper maximized window.

This is related with plasma and not your video card. Please post the output of inxi -Fayz and check your system is up to date with sudo pacman -Syu

Print’s out system information, what exactly you need to see? I doubt that my Battery, CPU, Network information is needed for troubleshooting.
What I should look for in this situation?

Summary

sudo pacman -Syu
[sudo] password for user:
:: Synchronizing package databases…
core is up to date
extra is up to date
community is up to date
multilib is up to date
:: Starting full system upgrade…
there is nothing to do

Yesterday after toggling “Always visible” after some time window still went under panel (no restart),
but today (wasn’t doing anything) it’s seems ok.

I just wanted to see what version of KDE you are using. It’s a pretty standard command. What branch are you using?

You can test of user data corruption by creating a new user and seeing if the problem still applies.