So... PC didn't properly wake this morning after being suspended overnight. But it did wake when I rebooted it, then suspended for a minute and woke it. This is confusing. Maybe the BIOS setting wasn't the issue after all or something else is affecting the performance. Back to the drawing board I go.
Edit: So... after testing things a couple of times back and forth, it seems like the wake from suspend gets borked whenever I bind and unbind my dGPU to a virtual machine! And, this might be related to the issue, I got a Steam error about X not being able to load after I unbind the dGPU from guest OS and reload kwin. Interesting... I'm using Wayland, and everything works fine after unbinding, except waking from suspend, which seems to freeze the system in addition to display not showing anything.