peopleinside Ahh, I see, thanks for the translation. 🙂
Alkir This is a limit in Flarum's code.
The best way to extend this would be to write an extension that overrides the Validator with a custom one.
Also note that the database (as of Beta 8.1) uses varchar(200) as its field class, so a migration would be necessary to increase the upper bounds past that point. This may or may not have repercussions on things like search performance.