Hi,
The issue has been fixed in Unreal Engine 5.7.1:
https://forums.unrealengine.com/t/5-7-1-hotfix-released/2681235
UE-348441 — DoF flickering with NVIDIA graphics driver 581
For older versions of Unreal Engine (5.5 and 5.6), you need to stay on the NVIDIA driver 577.00.