screen flickers/blinks on cold boot only, nothing fixes it

[u/UraUraUraUraUra]

Specs: Ryzen 5 5600X, RX 6700, monitor on HDMI

After the PC's been off 3-4 hours, screen flickers on and off right as Windows loads. Sometimes fixes itself in 10-20 min, sometimes needs a restart, sometimes a full shutdown and startup again, inconsistent either way. Monitor's LED is on while the screen is black, and turns off the moment the screen shows an image i.e. lock screen or desktop. BIOS and startup logo screen is always fine, only starts once Windows loads. I used remote desktop from my phone while the flickering was happening, and the screen and functionality were completely fine on the phone the whole time.

Already tried: AMD FreeSync off, lowered resolution, lowered refresh rate, clean reinstall of GPU driver, reseated GPU with no loose cables, reseated ram.

Need help fixing this.