I have identified one of the reasons for the frame drops: whenever there is a change in the devices listed in the Device Manager (such as being turned off or reconnected), FFXIV experiences a single frame drop. I have a USB mouse charging dock that, when connected to the computer, repeatedly prompts an "Unrecognized USB Device" pop-up. Although I have already blocked it in the system notifications, it seems that the changes in the Device Manager continue to cycle. Removing this device from my computer has resolved the issue, leaving only occasional frame drops.

I am still unable to enable some of the unique optimizations for the AMD graphics card on the older Windows 11 device, such as frame pacing and Enhanced Sync. Whenever these features are enabled, intermittent frame drops still occur.

However, this issue did not occur on a newly installed Windows 10. Connecting this device or using the unique features of the AMD graphics card did not cause any impact.