GUI flickering and stuttering with G-Sync enabled

[rockenren]

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OS and Version (please complete the following information):

• Operating System: Windows 10
• GPU: Nvidia RTX4070, two G-Sync compatible monitors with enabled G-Sync
• Shotcut Version: v25.12.31

Describe the bug
Monitor flickers and Shotcut GUI stutters while Shotcut is running when G-Sync is enabled.

As you can see on screenshot, Shotcuts window is GPU accelerated, but for some unknown reason its triggers G-sync even if G-Sync mode in Nvidia control panel set as "For fullscreen only applications".

Only disabling G-Sync completely resolves this issue, but this is not acceptable solution.

Maybe this is not Shotcut specific problem but a Qt6 issue (?) on Windows or Nvidia driver (?). I have a few other Qt6 based apps that have the same issue, but they dont require such extensive interaction via GUI as Shotcut.

Steps To Reproduce

1. Enable G-Sync
2. Start Shotcut
3. Move mouse cursor over any elements in Shotcut window.

Expected behavior
Option to disable HW acceleration for GUI would be nice.

Screenshots