Try going into your monitor OSD and see if you can change the Hz there, I had to change mine in the monitor onboard settings, not the PC settings..
AMD Ryzen 9 9900x, Asus Tuf Gaming RX 6700 XT, Asus Crosshair X870E Hero, 64gb Kingston DDR5 6000, Samsung 980pro 1tb NVME, Samsung 970 EVO Plus 1tb NVME, DeepCool Mystique 360 AIO, Antec Titanium 1000w.