I was able to fix the issue by simply completely removing the graphics drivers (not chipset drivers) using the amd cleanup utility, installing the minimal graphics drivers provided by ASUS for the laptop because I tried reinstalling only the graphics drivers using the auto-detect tool and I had the same problem resurface.
Now the windows loading animation takes maybe 12 seconds max and I'm at the login screen as usual. The bootlog looks fine as well. Everything works as it should. The whole driver verifier thing was unnecessary. I haven't tried the latest graphics drivers from amd yet (offline installation, not with the auto-detect tool) but I'm just gonna leave it like this with the latest OEM drivers dating back to march of this year. I tested the iGPU performance using aida64's GPGPU benchmark and it's exactly the same as it was before. I don't think there's any need to upgrade, especially knowing they dropped support for GCN/Vega.