Changes to fields output by comment_form in WordPress 4.4
A change in WordPress that just landed in trunk is to move the comment textarea to the top for logged-out users when replying. This is done largely with the goal to improve keyboard/focus navigation, but also aims to make it easier for end users to leave comments on WordPress sites. The change necessitated some filters and actions now being run in a different order. It also means that the HTML output by
comment_form will now be different.
If you use any of the hooks inside
comment_form, but especially
comment_form_after_fields, you are highly encouraged to test your code against the current WordPress nightly and report any issues on ticket #29974 so that any necessary adjustments can be made. Visual records and example code will help ensure everyone is satisfied with the final result.