LibreOffice randomly changes typeable character lenght in forms

I have to work with LibreOffice Base, and when I created a form to fill the table, used it it worked perfectly, but when I wanted to use again it randomly changed the maximum typeable character limit.

I mean for example, I could type "microsoft" for the first time, but after, it changed the limit randomly and now I only can type in "micr" then it's gone, no more characters accepted.