diff --git a/wp-includes/block-supports/border.php b/wp-includes/block-supports/border.php
index bb81e88134..a11c099d9e 100644
--- a/wp-includes/block-supports/border.php
+++ b/wp-includes/block-supports/border.php
@@ -152,7 +152,7 @@ function wp_apply_border_support( $block_type, $block_attributes ) {
  */
 function wp_has_border_feature_support( $block_type, $feature, $default_value = false ) {
 	// Check if all border support features have been opted into via `"__experimentalBorder": true`.
-	if ( property_exists( $block_type, 'supports' ) ) {
+	if ( $block_type instanceof WP_Block_Type ) {
 		$block_type_supports_border = isset( $block_type->supports['__experimentalBorder'] )
 			? $block_type->supports['__experimentalBorder']
 			: $default_value;
diff --git a/wp-includes/block-supports/colors.php b/wp-includes/block-supports/colors.php
index 053ec239dc..f14b718b88 100644
--- a/wp-includes/block-supports/colors.php
+++ b/wp-includes/block-supports/colors.php
@@ -17,7 +17,7 @@
  */
 function wp_register_colors_support( $block_type ) {
 	$color_support = false;
-	if ( property_exists( $block_type, 'supports' ) ) {
+	if ( $block_type instanceof WP_Block_Type ) {
 		$color_support = isset( $block_type->supports['color'] ) ? $block_type->supports['color'] : false;
 	}
 	$has_text_colors_support       = true === $color_support ||
diff --git a/wp-includes/block-supports/typography.php b/wp-includes/block-supports/typography.php
index 2358d304c4..bccde4f5c0 100644
--- a/wp-includes/block-supports/typography.php
+++ b/wp-includes/block-supports/typography.php
@@ -16,7 +16,7 @@
  * @param WP_Block_Type $block_type Block Type.
  */
 function wp_register_typography_support( $block_type ) {
-	if ( ! property_exists( $block_type, 'supports' ) ) {
+	if ( ! ( $block_type instanceof WP_Block_Type ) ) {
 		return;
 	}
 
@@ -85,7 +85,7 @@ function wp_register_typography_support( $block_type ) {
  * @return array Typography CSS classes and inline styles.
  */
 function wp_apply_typography_support( $block_type, $block_attributes ) {
-	if ( ! property_exists( $block_type, 'supports' ) ) {
+	if ( ! ( $block_type instanceof WP_Block_Type ) ) {
 		return array();
 	}
 
diff --git a/wp-includes/class-wp-block-supports.php b/wp-includes/class-wp-block-supports.php
index ee2791dd17..afc011803b 100644
--- a/wp-includes/class-wp-block-supports.php
+++ b/wp-includes/class-wp-block-supports.php
@@ -142,7 +142,7 @@ class WP_Block_Supports {
 		$block_registry         = WP_Block_Type_Registry::get_instance();
 		$registered_block_types = $block_registry->get_all_registered();
 		foreach ( $registered_block_types as $block_type ) {
-			if ( ! property_exists( $block_type, 'supports' ) ) {
+			if ( ! ( $block_type instanceof WP_Block_Type ) ) {
 				continue;
 			}
 			if ( ! $block_type->attributes ) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 85bc18bb7e..ced110f7d7 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-beta1-56741';
+$wp_version = '6.4-beta1-56742';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.