Hi, Klaus Sokoll
Welcome to the MicroSoft Community.
In response to your question about gradual clarity, unfortunately I have not succeeded in reproducing it. However I would like to suggest you try the following steps based on past experience:
1. Try a clean boot, as far as I know there are third-party apps that may affect the Edge browser's Start Tab page, extensions, etc., and that act on the registry, so you can try a clean start to rule out the impact third-party apps may have on the Edge browser;
How to perform a clean boot in Windows - Microsoft Support
Disclaimer: 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 so that it will help you get back on track.
2. Try to download the old version of Edge to see if it can start normally. The download link is as follows:
Download Edge for Business (microsoft.com)
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3. Try to create a new local account to see if the Edge browser can be opened normally, if it can be opened normally, it means that there may be a problem with the user profile. The method to create a new local account is as follows:
Create a local user or administrator account in Windows - Microsoft Support
If there is anything not clear or I can't understand your problem, please do not hesitate to let me know.
Best Regards
Martin | Microsoft Community Support Specialist