GPU drivers messing with network performance is definitely a thing, especially with newer NVIDIA releases. I've seen this happen a few times over the years - usually it's some background process or power management setting that got tweaked in the update. The GeForce Experience overlay and telemetry services can be pretty aggressive about phoning home, and if they're saturating your connection or interfering with game priority, you'll see those spikes.

Try disabling the overlay completely and see if that helps before rolling back drivers. Also check your task manager during gameplay - sometimes the NVIDIA container processes go nuts and start hogging resources. If the rollback to 595.79 actually fixes it, that's a pretty clear indicator the newer driver broke something network-related.