WordPress full changelog

Conditionalise metaboxes based on Zoom Out (#66742)
Block toolbar: restrict visible child calculation to known blocks (#66702)
Optimize getVisibleElementBounds in scrollable cases (#66546)

The following core tickets from Trac are fixed:
All links underlined due to CSS specificity bump for top-level element-only selectors.
is_utf8_charset() undefined when called by code in compat.php (causes a fatal error).
PHP Fatal error: Uncaught Error: Object of class WP_Comment could not be converted to string.
Update the $_old_files array for 6.6 (which caused security plugins to flag the files).
Toolbar: consider moving user menu to a higher priority (after most plugins).
Layout: Invalid CSS for nested fullwidth layouts with zeroed-out custom padding.
Classic Editor Category metabox shows all categories, without scrolling.
The following block editor issues from GitHub are fixed:
Elements: Avoid specificity bump for top-level element-only selectors.
Navigation block: Allow themes to override block library text-decoration rule.
Fix invalid css for nested fullwidth layouts with zero padding applied.
Prevent empty void at the bottom of editor when block directory results are present.
Pattern overrides: Ensure “Reset” button always shows as last item and with border.
Global Styles: Disable “Reset styles” button when there are no changes.
Fix: Removed shuffle button when only 1 pattern is present.
fix: wp icon focus issue.
useBlockElement: return null until ref callback has time to clean up the old element.

The following core tickets from Trac are fixed:
All links underlined due to CSS specificity bump for top-level element-only selectors.
is_utf8_charset() undefined when called by code in compat.php (causes a fatal error).
PHP Fatal error: Uncaught Error: Object of class WP_Comment could not be converted to string.
Update the $_old_files array for 6.6 (which caused security plugins to flag the files).
Toolbar: consider moving user menu to a higher priority (after most plugins).
Layout: Invalid CSS for nested fullwidth layouts with zeroed-out custom padding.
Classic Editor Category metabox shows all categories, without scrolling.
The following block editor issues from GitHub are fixed:
Elements: Avoid specificity bump for top-level element-only selectors.
Navigation block: Allow themes to override block library text-decoration rule.
Fix invalid css for nested fullwidth layouts with zero padding applied.
Prevent empty void at the bottom of editor when block directory results are present.
Pattern overrides: Ensure “Reset” button always shows as last item and with border.
Global Styles: Disable “Reset styles” button when there are no changes.
Fix: Removed shuffle button when only 1 pattern is present.
fix: wp icon focus issue.
useBlockElement: return null until ref callback has time to clean up the old element.

The following core tickets from Trac are fixed:
Block Hooks: Incorrect context passed when setting ignored hooked blocks metadata
Patterns menu item, put back the context parameter.
wp_localize_script() on login_enqueue_scripts hook change in behavior
Some PHPUnit Tests are failing (test changes only)
Autoprefixer warning in `src/wp-admin/css/media.css` when running `precommit:css` Grunt task
Fatal error when passing non-strings to `WP_Translation_Controller::load_file()`
Classic Theme with theme.json attempts to load templates
Layout: Output of base layout rules conflicts with wide alignment of blocks in classic themes
Fix get_item_features() in class-avif-info.php
6.5 adds the “is-layout-constrained” class to the wrong place for classic themes
Plugin management: AJAX plugin activation consequences
The following block editor issues from GitHub are fixed:
#60489 – Layout: Skip outputting base layout rules that reference content or wide sizes if no layout sizes exist
#60620 – Fix inserter pattern pagination focus loss
#60608 – Fix static posts page setting resolved template
#60641 – Font Library: Fix modal scrollbar
#60661 – Interactivity API: Allow multiple event handlers for the same type with data-wp-on.
#60668 – Layout: Always add semantic classes
#60845 – List View: Fix stuck dragging mode in UI in Firefox when dealing with deeply nested lists
#60764 – Don’t output base flow and constrained layout rules on themes without theme.json