unfortunately the new version 3.6.73 does not allow you to submit the form

Hello,
My form, which worked fine yesterday with version 3.6.72, does not want to work today with version 3.6.73.
I cannot submit the form, even though all the required fields are filled in with the correct data.

And consol says:

jquery-migrate.min.js?ver=3.3.2:2 JQMIGRATE: Migrate is installed, version 3.3.2

form-submission.js?ver=3.6.73:1 
{last_name: {…}, first_name: {…}, email: {…}, password: {…}, first_checkbox: {…},?…}email: email: {value: true, message: "This field must contain a valid email"}required: {value: true, message: "This field is required"}__proto__: Objectfirst_checkbox: required: {value: false, message: "This field is required"}__proto__: Objectfirst_name: required: {value: true, message: "This field is required"}__proto__: Objectlast_name: required: {value: true, message: "This field is required"}__proto__: Objectpassword: required: {value: true, message: "This field is required"}__proto__: Objectsecond_checkbox: required: {value: false, message: "This field is required"}__proto__: Object__proto__: Object

The page I need help with: [log in to see the link]