Wish I read this before paying the 5000 USD for my ASUS ROG Strix Scar 18 RTX 5090 G835LX, I have had nothing but issues with it while trying to game with their inbuilt MUX switch AKA Ultimate Mode where the laptop screen is routed directly to the RTX 5090 Laptop version dGPU.
I am handicapped by using it in Optimus mode only - (not even Advanced Optimus) - been like this for the past 2 months.