Hello DMITRYLYSAK,
Welcome to Microsoft Community.
We noticed that you seemed to publish two similar threads, so we merged the two threads together.
I'm guessing that this may be due to performance issues, or to put it more bluntly, your Surface Pro 11 May be slowing down for some reason.
Under normal circumstances, the performance of the Snapdragon X processor on the Surface Pro 11 should be significantly better than the Intel Core m3 processor, so the first thing I recommend you do here is to try to optimize the performance of the Surface Pro 11:
Tips to improve PC performance in Windows - Microsoft Support
That's because a flickering white background for about half a second when you open a folder is usually a sign that the computer is loading a dark mode, but it didn't happen on my Surface Pro 10. But I need to emphasize that similar situations have occurred in some other brands of computers. In other words, all computers may experience this phenomenon, but some devices are more powerful, so the loading speed is so fast that you can hardly see the white background is already done.
Another thing to look for is if you have some third-party software installed in your Surface Pro 11. If you have used some theme software, because such software will interfere with the theme setting of the system, it will cause this phenomenon. So I recommend trying a clean boot which starts Windows with a minimal set of drivers and startup programs. It can be used to determine whether a background service or program is interfering or causing a problem.
These steps of "clean boot" might look complicated at first glance. However, to avoid any trouble for you, please follow them in order and step-by-step.
Once the clean boot is complete, test your Surface and see if the performance issues have improved.
Best Regards,
Mitchell | Microsoft Community Support Specialist