Hello, Christoph Stuetz.
Welcome to the Microsoft community.
Thank you very much for explaining the problem.
What I want to explain to you is that the problem of OneDrive shared folders showing up as "direct internet access" that you described above is a hot issue that has occurred recently. We have received feedback from users from all over the world who have encountered this issue. The problem is still under investigation and correction. The OneDrive development team apologizes for any inconvenience this issue may cause.
More information about this issue is described in the support article <Add and sync shared folders to OneDrive for home - Microsoft Support>
https://learn-attachment.microsoft.com/api/attachments/a6892c34-59d6-403f-b529-f89ee7b43c5e?platform=QnA&fud_access=hC1SxZhn7m%2FZQJkOIiOVstu10yTQgXS4A%2FDBzZTg8nbaCgIogkrcDydMeI5Y4za2dOqDdWtsG2JNS3E35V60i9TiGHR7STMpJHheeXuDvO8nwjUlqCBHhJ0NDvuYN7OSbqx14ocCqbcTxr3gfcsxbbjdCRgqg82Bgc7w8q4y4CmrQuIMuutdgQ%2BPmFTyDVsdAo%2BB7y2dAmZEfGN6aBvTy8UA8Y6NCu2Y57Sioh5Im%2BBNZZiofAcdZGZC6sa9ylUVS6heRddFDWKUPYJErRXTs3VhQt2j5vqoH2zUtUyw1B0Q0o0UrtonT7YK5LC5jR%2BsVMi5bmW8WW5l2dNMTMZXTfsRe%2FME3%2BeUU6XK6LB4MIJ5dwQ7B4qHX9vPEX6QMQvhvvsXaG%2BCbf4N80AgNgFu3%2BFLD%2FOlD2anmkOOSrn7yc8%3D
Since the Microsoft community is just a community for technical discussions, I can't attend to development-related content, but I'll continue to monitor the issue for you in this answer thread and share the latest progress on the issue with you as soon as possible.
At the same time, I found the last channel of users to send reports and feedback on this issue, which was opened by the OneDrive team
To send feedback, you can provide feedback at the following link: OneDrive · Community (microsoft.com)
You can also open the OneDrive mobile app, shake it, and click Report to send it. You can take a screenshot of the issue you're experiencing and provide a detailed description to the OneDrive engineering team (or send feedback about the issue via the OneDrive link (live.com)English only
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Thus, they can bring together the different manifestations of the problem faced in order to fully understand the full picture of the problem and provide a more complete solution. We apologize again for any inconvenience this issue has caused
▲ I will continue to follow up on the issue for you in this response thread and share the latest progress on the issue with you as soon as possible. While you wait for the fix, you can alternatively visit OneDrive for the web temporarily.
Thank you very much for your🙂 understanding
Best regards
Hannah.Z- MSFT |Microsoft Community Support Specialist