AW2724DM, Nvidia, HDR mode, brightness flickering

Recently bought this monitor, everything is fine except HDR mode. If i turn this feature on in Menu OSD as HDR600, and then also turn it on in Windows 11 screen settings, it causes consistent changing of brightness for 35 seconds, about 15 times with 2 seconds interval, like 100nit - 600nit, back and forth, after it settles down. Graphics card Nvidia 5070 Ti, DP (display port) connection, altered every possible setting as I could, performed factory resets, nothing changes firmware is up to date M2B104.

Any ideas on its cause are much appreciated.