[Gelöst] Ajax request gets redirected from one domain to another on multisite setting

Background of the issue:
I am making a dynamic form for our client site using ajax calls. Some fields appear depending on what the user inputs into the form, like a success or an error message for the promo code field. While it works properly on the English version of the form (versteckter Link), I have noticed that the French version of the form (versteckter Link) doesn't work properly and redirects my ajax calls from .fr/wp-admin/admin-ajax.php to .com/wp-admin/admin-ajax.php, wiping the payload content of the request and returning a 400 error. I have tried to activate or deactivate the ajax cookie setting and searched in the .htaccess without much success. The ajax calls work when using subdomains instead of domains in a development environment, making me think that this redirection is the real problem.

Symptoms:
Ajax calls on the French version of the form redirect from .fr/wp-admin/admin-ajax.php to .com/wp-admin/admin-ajax.php, wiping the payload content and returning a 400 error.

Questions:
Is there a way to deactivate that ajax redirection from one domain to another on multisite setting?