Created attachment 846731 [details]
Taken right after boot to desktop, with "drm.debug=0x1e" & "log_buf_len=4M"
kernel parameters set in GRUB2.

Overview:
At the start of OS booting, colors are fine (black is deep). During booting, at
the moment the Intel driver i915 is loaded, screen flickers once and colors get
degraded (black gets grey). Note I'm not using Plymouth so I'm looking at the
black tty. After the boot, when executing 'xrandr --output DP-1 --set
"Broadcast RGB" Full', I can confirm the colors get immediately fixed up (white
is light, black is deep, colors are more saturated). The issue is related to
another bug report in upstream and is resolved for some people but not for me:
https://bugs.freedesktop.org/show_bug.cgi?id=107476.

Steps to reproduce:
1) Start the PC.
2) Watch the boot console with Plymouth disabled.
3) Pay attention to the moment the screen flickers and the graphics driver is
loaded.

Actual results:
Step 3) is the moment colors get degraded. And stay that way.

Expected results:
After the screen flickering during the step 3), colors should stay the same.

Affected Linux kernel versions:
The standard Linux version in openSUSE Leap 15.2: 5.3.18
The newest stable Linux from the Kernel:stable repo: 5.11.2

Affected hardware:
GPU: Intel Iris Plus Graphics 640 (Which uses the i915 kernel module = the
common denominator of the problem reported by other people.)
LCD monitor: Iiyama ProLite XB2483HSU-B3 (Supports 24 bit colors, like other
reported affected monitors.)