The personal data FormFinch has on you depends on your situation. Any data that is not mentioned will be anonymized and therefore not considered personal.
FormFinch only collects personal data that is absolutely necessary for FormFinch to function or demanded by laws and regulations. In short this comes down to your email address and when you are subscribed to a paid plan of course you payment information. All data we collect is described and can be read in full detail in our Privacy Statement.
FormFinch provides a service that enables our users to create their own forms and collect submissions. The content of the form and the submitted data belong to the owner of the FormFinch account. The only thing FormFinch does with your data is store it in an encrypted database and modify, delete or export it when our customer chooses to via the FormFinch application. In normal circumstances no one but the owner of the FormFinch account has access to the data you’ve submitted unless we are required by the law to so.
So as long as you trust the person, company or organization that created the form and are not breaking any laws by doing so, you have nothing to worry about.