Hi - to reproduce:
1.Create a simple 1 text field form and make the text field required.
2.Add this form to some page or post and using the orbital theme/gutenberg editor, change the button’s color
3. Enable the AJAX toggle (it works fine if AJAX is disabled)
4.Publish the page and go to that page and now submit the form without entering anything into the text field so that the form fails validation
5. Observe the default blue color is now showing on the button instead of the other color you had set.
Expected result - colors set via the Gutenberg block editor should remain even in form validation error.
See loom: