Well, that.
I started playing K+M, certain that GOG Galaxy wouldn't recognize my (wired) PS4 controller, but surprisingly it did, and played most of the game like that. Unfortunately it doesn't recognize it anymore after the 1.06 patch.

Made sure Steam was closed and validated/repaired updated files so far.
Tried changing USB ports but nothing happened.

Any ideas on how to fix this? Thanks in advance.

Microsoft works against this also..

Get the Xbox controller Emulator to translate PS4 controller to Xbox.

Thanks for the workaround advice, but I'd rather add the GOG version as a non-Steam game until this get a specific fix than using controller emulators.

Also, I'd like to know if anybody experienced something like this after the patch.
Doubt I must be the only one playing with a PS4 controller on PC.

No. DS4 exists because Sony couldn't be arsed to make a proper driver.

I agree with Mobeeuz. Sony finally had to give in to offer proper official drivers for Windows 10
(besides using MS servers for the PS streaming service on America, having to comply with crossplay platforming to keep their platform relevant against PCs, etc).

And Steam allowed for Dualshock support even before Sony allowed official drivers.
I remember finishing Phantom Pain and Witcher III two weeks after release with a Dualshock4 and without external drivers.

The Controller issue spanned across more than just PS3 - PS4 controllers M$ updated anned X360 in order to secure more sales for newer stuff and wrote it off as a security issue, This prevented driver loading for the X360 and still causes problems etc and generic controllers that use Standard Joypad get screwed also, This is why Xbox Control Emu came about as it passes generic controls off as Xbox controls, for a Time the DS3 was able to be used as a Generic Controller BUT MY SECURITIESSS>. Valve used a translation like the Xbox Control Emu and even then it would not always work with certain games, XCE worked every time once setup dump the DX hooks into folder and off it went didn't need the GPU hooks from steam interfering with the framerate and stability to boot.

Launch the game via Steam to use SteamController API. It has full support of DS4.