As said above:
- Disabled overlays in all programs (Discord, GeForce Experience, and Steam)
- Disabled other programs that start at launch (other than the Realtek audio drivers)
- Checked the Windows Event Viewer for errors (there's nothing, just a "the system stopped unexpectedly" error on the next boot-up)

In addition:
- Checked that Windows 10 is up to date
- Checked that my video and audio drivers are up to date
- Monitored CPU and GPU temperature (both are fine, even when the issue occurs)
- Ran Memtest86 to check for memory errors

Other graphics-intensive games have run fine on this PC. Control, Forza Horizon 4, and The Outer Worlds all ran flawlessly. As does FFXIV, except when encountering spots in these specific cutscenes.