Firstly thank you very much for your help! It is an interesting bug nevertheless.
Thing is, I might need to change the username through the db, cause the route is not available
Can you provide me with a query?
I think this is not possible because then I would ban the many names that start with Σ in greece (and I will essentially break Facebook logins for those users). Can I ban a specific regex pattern? so that I ensure that the Σ is at least at the end?