adobe premier

Please post a screenshot of that.

That is usually an outdated video driver

Do not count on Windows to be fully up to date when it comes to device drivers
Go to the vendor site to be sure you have an updated driver for your graphic adapter
.
nVidia Driver Downloads https://www.nvidia.com/Download/index.aspx?lang=en-us
-for all Adobe programs use the STUDIO driver, not the GAMING driver
-To achieve the highest level of reliability, Studio Drivers undergo extensive
-testing against multi-app creator workflows and multiple revisions of the top
-creative applications from Adobe to Autodesk and beyond
.
If you have a laptop you MAY also need to check for a laptop specific nVidia driver
-SOME laptops require an approved driver from the laptop company, not nVidia
.
AMD/ATI Driver https://www.amd.com/en/support
.
Intel https://downloadcenter.intel.com/product/211969/Intel-HD-Graphics-Family
https://www.askwoody.com/newsletter/free-edition-working-with-the-intel-driver-support-assistant/

Hi Dirk,

You may want to communicate in English as this is an international forum.

To your issue...

Could you perhaps share your computer specs? CPU, GPU, RAM amount etc.
You mention transitioning to Win11. On the same machine where you had no issues before? Or a complete new machine?

What is the format and codec of the files you are using?

If you go to File -> Project Settings -> General, what is selected there as the playback engine?

In general it sounds like either a hardware compatibility or graphics driver related issue but we need to have a bit more details.