It is currently possible to Submit forms with text fields that are only filled with spaces despite being flagged as mandatory to fill in. I have tried to use a regex expression to avoid that but it will not prevent the user from submitting the form. Also tried to limit the amount of characters via regex to 100 I was able to submit over 100 characters in a text field in a form. I used the following expression:
^(?!\s)(?!.\s$)(?!\s$).{1,100}$