You should try a clean boot via msconfig without any background programs - this can help to find the the app that interrupting in the background.

Update to latest NVIDIA driver again.

Disable any overlays (Discord, Rivatuner etc)

Uninstall all unneeded software (McAffee, VPN Software that is not needed)

You can also try "LatencyMon" running to check if there is a app causing a drop in latency.

If none of this help, consider reinstall windows completeley. You have some tools installed, that coudl cause unwanted changes (Registry Edit).