The new FSE editor uses a new filter, if you want to hook into that you can do it in two ways:
By hooking the individual block rendering:
add_filter( 'render_block_core/navigation-link', 'test_render_navigation_link', 10, 3);
function test_render_navigation_link($block_content, $block) {
$attributes = $block["attrs"];
// string replace the href if you want, by checking the content of $attributes
return $block_content;
}
or by hooking the prerender for the entire navigational menu:
add_filter( 'block_core_navigation_render_inner_blocks', 'replace_nav_blockitem_href');
function replace_nav_blockitem_href( $items ) {
// Loop through the items (they are nested)
foreach ($items as $key => $item) {
//recursive loop through $item->inner_blocks
//once you have found your item then set the attribute url to empty
$item->parsed_block["attrs"]["url"] = null;
}
return $items;
}
The rendering of the navigation item will not output the href if the url is empty, this can be seen in the source code of the rendering:
https://github.com/WordPress/wordpress-develop/blob/0cb8475c0d07d23893b1d73d755eda5f12024585/src/wp-includes/blocks/navigation-link.php#L173
This is the line where the first filter is called:
https://github.com/WordPress/wordpress-develop/blob/28f10e4af559c9b4dbbd1768feff0bae575d5e78/src/wp-includes/class-wp-block.php#L306
This is the line where the second filter is called:
https://github.com/WordPress/wordpress-develop/blob/0cb8475c0d07d23893b1d73d755eda5f12024585/src/wp-includes/blocks/navigation.php#L512