Hi, everybody! Can I ask you a question? How can I make it so that when a user from another site after payment through stripe gets to the registration page bubble and in the email field, first name and last name were pulled automatically from stripe?

What stripe do you use? Plugin, API calls?
Either way there will be API call that take customer to payment link and when payment succeeded, it takes user to return URI. You can set this url to something like ( YourSiteDomin?status=success&page=signup&session-id=session ID).
In this example i supposed you are using one page app and get the sign up page from Parameters. If not, then use something like
( YourSiteDomin/sign-up?status=success&page=signup&session-id=session ID).
In both cases user will be directed to sign up page. You can have workflow ( do everytime > get data from URL ( status=success). "Now you know the payment was successful and user is directed to sign up.
Actions > retrive payment session from URL
Save the email etc from the session in custom states and pre fill the inputs.
You can set the inputs conditions like
When get data from URL (session-id) is not empty> initial value ( the state u put) and you can mark it as not editable if u want to force no change.

I customize through API I need to customize only the bubble and stripe sides