I got the new Windows 11 insider preview. So I just set up my Windows 11 a few weeks ago. HOT TOPIC: Speed Up Windows 11 | Optimization For Gaming and Development Method 1, Remove Activate Windows 11 Watermark Permanently Using Watermark Disabler (Universal Watermark disabler) And you can see this Watermark only in dev or beta channel build.
This Watermark is just to tell your current windows version. so many insiders will get this prompt to identify the current build version. So why is this Watermark appearing in this build? Because Microsoft is going to release a stable build.