Ubuntu 20.04 on AMD APU doesn't see maximum display resolution

Suddenly, Ubuntu 20.04 stopped seeing maximum screen resolution and only sets to 1600x900.

I tried to install downloaded from amd.com Ubuntu drivers, but it didn't help.

Info about workstation:

$ uname -a
Linux mypc 5.8.0-59-generic #66~20.04.1-Ubuntu SMP Thu Jun 17 11:14:10 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.2 LTS
Release:    20.04
Codename:   focal

$ sudo lshw -C video
  *-display                 
       description: VGA compatible controller
       product: Renoir
       vendor: Advanced Micro Devices, Inc. [AMD/ATI]
       physical id: 0
       bus info: pci@0000:0a:00.0
       version: d8
       width: 64 bits
       clock: 33MHz
       capabilities: pm pciexpress msi msix vga_controller bus_master cap_list rom
       configuration: driver=amdgpu latency=0
       resources: irq:30 memory:d0000000-dfffffff memory:e0000000-e01fffff ioport:e000(size=256) memory:fca00000-fca7ffff memory:c0000-dffff

$ inxi -Gx
Graphics:  Device-1: Advanced Micro Devices [AMD/ATI] Renoir driver: amdgpu v: kernel bus ID: 0a:00.0 
           Display: x11 server: X.Org 1.20.9 driver: amdgpu resolution: 1600x900~60Hz 
           OpenGL: renderer: AMD RENOIR (DRM 3.38.0 5.8.0-59-generic LLVM 11.0.0) v: 4.6 Mesa 20.2.6 direct render: Yes

$ cat ~/.config/monitors.xml 
<monitors version="2">
  <configuration>
    <logicalmonitor>
      <x>0</x>
      <y>0</y>
      <scale>2</scale>
      <primary>yes</primary>
      <monitor>
        <monitorspec>
          <connector>DisplayPort-0</connector>
          <vendor>GSM</vendor>
          <product>LG Ultra HD</product>
          <serial>0x00038da8</serial>
        </monitorspec>
        <mode>
          <width>3840</width>
          <height>2160</height>
          <rate>59.996623992919922</rate>
        </mode>
      </monitor>
    </logicalmonitor>
  </configuration>
</monitors>

I remember it was set previously, but unexpectedly it doesn't show maxium screen resolution. Reboot doesn't help.

UPD After a sleep the resolution became normal. Unfortunately I didn't capture xrandr output before. Currently it's

$ xrandr
Screen 0: minimum 320 x 200, current 3840 x 2160, maximum 16384 x 16384
DisplayPort-0 connected primary 3840x2160+0+0 (normal left inverted right x axis y axis) 600mm x 340mm
   3840x2160     60.00*+  30.00  
   2560x1440     59.95  
   1920x1200     60.00  
   1920x1080     60.00    59.94  
   1600x1200     60.00  
   1680x1050     60.00  
   1600x900      60.00  
   1280x1024     60.02  
   1440x900      60.00  
   1280x800      59.81  
   1280x720      60.00    59.94  
   1024x768      60.00  
   800x600       60.32  
   720x480       60.00    59.94  
   640x480       60.00    59.94  
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
HDMI-A-1 disconnected (normal left inverted right x axis y axis)
HDMI-A-2 disconnected (normal left inverted right x axis y axis

And now

$ inxi -Gx
Graphics:  Device-1: Advanced Micro Devices [AMD/ATI] Renoir driver: amdgpu v: kernel bus ID: 0a:00.0 
           Display: x11 server: X.Org 1.20.9 driver: amdgpu resolution: 3840x2160~60Hz 
           OpenGL: renderer: AMD RENOIR (DRM 3.38.0 5.8.0-59-generic LLVM 11.0.0) v: 4.6 Mesa 20.2.6 direct render: Yes

The resolution now is as expected resolution: 3840x2160~60Hz