My forms were working fine with AJAX based on this document: https://learn.getgrav.org/16/forms/forms/how-to-ajax-submission
But since some recent updates, the AJAX part ceased to work. Now after submission of the form, the whole page is reloaded and the response message appears alone on this empty page.
When I disable the captcha, things work fine.
After some testing:
It works with Grav v1.6.19 and Form v3.0.8.
But fails when I update to Form v4.0.0.