BIOS 327 is here 

For screen flickering try driver from this thread (posted by Annaby_ROG) https://rog-forum.asus.com/t5/gaming-notebooks/asus-zephyrus-duo-16-2023-freezing-flicking/td-p/939109/page/10 driver V31.0.14038.6002 helps for Zephyrus DUO 2023 (same hardware...

It backs to normal after launch some game to switch dGPU on. Try reinstall nvidia drivers.