HP Z Display Z32 31.5 inch 4K UHD (3840 x 2160) WLED LCD Black Pearl … I also suspected the laptop itself, but then I tried to connect it via usb-c to usb-c to different 4K monitor and it worked perfectly and never dropped connection. Now I found in Q&A for this display on Amazon that another customer had the same problem with DP connection.
https://www.amazon.com/HP-Business-Z27-LED-Monitor/dp/B07CKXCBWB

