Plugin to workaround gutenberg issue #53477

classic-block-resticky.php

<?php
/**
 * Plugin Name:       Classic Block Resticky
 * Description:       Ensures the classic block’s formatting toolbar is sticky when custom fields are present.
 */

add_action( 'admin_footer', function() {
	// Bails unless on a block editor screen
	if ( ! get_current_screen()->is_block_editor() ) return;

	?>
	<style>
		.has-metaboxes .edit-post-visual-editor { overflow: unset; }
		/* Prevents overlap of formatting toolbar and the block toolbar */
		.has-metaboxes .is-selected .block-library-classic__toolbar { top: 59px; }
	</style>
	<?php
}, 1000);