Does your display support HDR?
It does, but I don’t keep it enabled. Thanks to your hint, I’ve figured out the reason: I left DXVK_HDR=1 as a global variable, and for some reason, this game is affected (even though there’s no HDR option in the settings). Strangely, even if I enable HDR at the desktop level (Plasma 6.2), the colors remain washed out. Anyway, removing the DXVK_HDR variable solves the problem. Thank you.
This game is rendered in washed-out colors when using DXVK (no problem with Wine D3D).
DXVK:

WineD3D:

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