My screen has just done the same thing. 

Razer Blade 15 (Early 2022 Model)  RZ09-0421 | i7-12800H | QHD-240Hz | 32GB | 1TB | RTX3080TI.

Purchased in Sept 2023 but rarely used as I have the PC. I didn't do any updates at the time. I was mid editing using an external monitor and all of a sudden it happened like a switch being turned on. I was 2 hours into editing. The laptop its self was hot as it always is. 

I've always had to have this laptop on top of an external laptop fan cooler due to the heat it generates. especially nearer the screen at the top of the keyboard. 

I much prefer using windows devices but my M1 Max after hours of editing doesn't produce any heat in comparison to the Blade. The point of a laptop is so you can use them on your lap right? Well this cannot be used on your lap unless you want 3rd degree burns.

Regardless, the heat I live with on a desk, but the screen with lines through it I cannot.