Forms / PayPal integration Issues

I have a Form that is using PayPal. The problem is that when I click Submit, the pop up form does not disappear, allowing the PayPal dialogue box to show. I have to close the Form box, to see the PayPal form. Here is the website page in question;
https://ucbma.com/food-truck-rally/2024-food-truck-vendor-application

Here is a link to a small video showing the issue.
https://www.dropbox.com/scl/fi/kttsc589wmgmkitqm05c6/FTR-Vendor-Application-Google-Chrome-2024-03-11_12-15-34.mp4?rlkey=ddkkfxh2j0wpd8xp2bnduyp0i&dl=0

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