Hi Unsuriati,
Welcome to Microsoft Community.
I'm Hahn and I'm here to help you with your concern.
It seems that you have modified the registry to disable the new context menu in Windows 11. This may have affected the ability to open folders in new tabs with the middle mouse button. Unfortunately, there is currently no official setting to enable both the old context menu and new tab functionality.
To implement this functionality, you may need to seek out other third-party tools to add tabs to File Explorer.
Microsoft attaches great importance to user experience, you can submit your ideas and suggestions through the Feedback Hub, and the development team will regularly review submissions for ideas or fixes.
Send feedback to Microsoft with the Feedback Hub app - Microsoft Support
Please share the feedback link here after submitting as it will allow others on the forum to vote for your submission, including me. More votes will lead to more visibility and higher priority to the development team.
I hope this helps. If there is anything not clear, please do not hesitate to let me know.
Your Sincerely
Hahn - MSFT | Microsoft Community Support Specialist