Quick update. I found the firmware updates took place via Windows Update. So I went into Windows Updates and installed the latest firmware version 0.1.8.1 under "Optional updates", and that fixed my problem. 165Hz works now on USB C via Display port!
I have a G15 5511 with the RTX 3060. Been using an external monitor @ 165Hz all this while over USB C with a DP cable, but it suddenly stopped working today. The monitor can only work on 59Hz now. Update history shows a Dell firmware update 1.7.0 was executed today, which is likely the culprit. Anyone with a similar issue or a fix to this?
Dell G15 - High refresh rates suddenly not working on monitor over USB-C