When in focus, the Application Panel background gray is 'blinking' - meaning it's shifting between two shades of gray.

Hi ​@wondrack,

Thanks for reporting this and sorry to hear that you experience this. Adding to the expert's suggestion, could you please confirm your operating system details and the exact InDesign version you're using? If you're not already on the latest Windows or macOS update available for your system, please install any pending updates and test the behavior again.

If the issue still persists, please let us know whether you're using an external monitor and if the blinking effect occurs only when connected to it, or whether it also happens on the primary display. Additionally, could you please share a short screen recording demonstrating the issue in action? 

Looking forward to your update.

Thanks,
Abhishek

Does unchecking Preferences > GPU Performance > GPU Performance and restarting Indesign make a difference?