Load Combined Core Block Assets

Description

This is a workaround for sites experiencing any issues with the ability introduced in WordPress 6.9 to load block styles on demand in classic themes. The known issues have been fixed during the 7.0 release cycle with the following commits:

• r61076: Script Loader: Fall back to hoisting late-printed styles to end of HEAD if wp-block-library is not enqueued.
• r61122: Script Loader: Load block styles on demand in classic themes even when wp-block-styles support is absent.
• r61174: Script Loader: Improve hoisted stylesheet ordering (in classic themes) to preserve CSS cascade.
• r61554: Script Loader: Preserve original CSS cascade for classic themes when hoisting late-printed styles.
• r61945: Script Loader: Refine hoisted stylesheet ordering to preserve original CSS cascade in classic themes.

If running a classic theme (i.e. not a block theme), this plugin filters should_load_separate_core_block_assets to be false. This has the effect of reverting a change introduced in 6.9 where classic themes now load separate core block assets on demand by default.

Note that this plugin should be considered temporary until any issues are resolved in 7.0. At any time, you can test whether any issues remain by adding ?should_load_separate_core_block_assets=true to any frontend URL; this restores the default behavior in WP 6.9.

This workaround should be temporary because there are performance benefits to loading separate core block assets. They can be loaded on demand just when they are used, as opposed to loading the large single combined wp-block-library stylesheet. Loading separate block styles on demand reduces the amount of CSS which should improve page load time. Nevertheless, as explained in the dev note, some sites may be built in a way that fundamentally does not work with loading separate block styles on demand. For these sites, this plugin is available to retain the old behavior.