HP Elitebook with external display and color issue

[deloptes <emanoil.kotsev@deloptes.org>]

Hi,
I don't know how to explain my problem, but I try hoping that someone would
understand and help me fix it.

So I have one HP Elitebook (I think it is 820 G2) with 16GB RAM and Intel(R)
Core(TM) i5-7200U CPU @ 2.50GHz.

The issue is that when it starts with its own display the colors are OK, but
as soon as I activate an additional display the colors get messed and it is
looking ugly like described
https://h30434.www3.hp.com/t5/Notebook-Video-Display-and-Touch/820-g1-Ubuntu-Screen-artifacts/m-p/7029819/highlight/true#M188601)

It is not clear to me what should I do to solve it.

Thank you in advance

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