I would like to take a look at the problem. Could you share the form to me, firstname.lastname@example.org? Do you know which field is likely the issue, and how many texts you input to that field?
There is a maximum of 10,000 chars for each cell in the table so a field value can't have more than 10,000 chars.
You could add a maximum num of chars restriction for your text field (see the property panel of that text field) so the person would be warned and prevented from entering more chars than the limit.