Using an old removed alias for shared mailbox doesn't work

What I did: I removed an alias from an user because I wanted to use it as shared mailbox. When creating it, everything works just fine. When opening in from webmail client, however, I have this: <img width="566" height="95" alt="Image" src="https://github.com/user-attachments/assets/c4503afb-726f-46c8-88df-a6099e5612c4" /> If I use anything else for the shared mailbox name, it works (test2 instead of test)