diff --git a/src/wp-includes/class-wp-theme-json.php b/src/wp-includes/class-wp-theme-json.php
index afff53f9da..700cb20f7e 100644
--- a/src/wp-includes/class-wp-theme-json.php
+++ b/src/wp-includes/class-wp-theme-json.php
@@ -779,7 +779,7 @@ class WP_Theme_JSON {
 			if ( empty( $result ) ) {
 				unset( $output[ $subtree ] );
 			} else {
-				$output[ $subtree ] = $result;
+				$output[ $subtree ] = static::resolve_custom_css_format( $result );
 			}
 		}
 
@@ -1958,10 +1958,6 @@ class WP_Theme_JSON {
 	/**
 	 * Returns the style property for the given path.
 	 *
-	 * It also converts CSS Custom Property stored as
-	 * "var:preset|color|secondary" to the form
-	 * "--wp--preset--color--secondary".
-	 *
 	 * It also converts references to a path to the value
 	 * stored at that location, e.g.
 	 * { "ref": "style.color.background" } => "#fff".
@@ -1969,6 +1965,10 @@ class WP_Theme_JSON {
 	 * @since 5.8.0
 	 * @since 5.9.0 Added support for values of array type, which are returned as is.
 	 * @since 6.1.0 Added the `$theme_json` parameter.
+	 * @since 6.3.0 It no longer converts the internal format "var:preset|color|secondary"
+	 *              to the standard form "--wp--preset--color--secondary".
+	 *              This is already done by the sanitize method,
+	 *              so every property will be in the standard form.
 	 *
 	 * @param array $styles Styles subtree.
 	 * @param array $path   Which property to process.
@@ -2018,20 +2018,6 @@ class WP_Theme_JSON {
 			return $value;
 		}
 
-		// Convert custom CSS properties.
-		$prefix     = 'var:';
-		$prefix_len = strlen( $prefix );
-		$token_in   = '|';
-		$token_out  = '--';
-		if ( 0 === strncmp( $value, $prefix, $prefix_len ) ) {
-			$unwrapped_name = str_replace(
-				$token_in,
-				$token_out,
-				substr( $value, $prefix_len )
-			);
-			$value          = "var(--wp--$unwrapped_name)";
-		}
-
 		return $value;
 	}
 
@@ -3488,4 +3474,52 @@ class WP_Theme_JSON {
 
 		_wp_array_set( $this->theme_json, array( 'settings', 'spacing', 'spacingSizes', 'default' ), $spacing_sizes );
 	}
+
+	/**
+	 * This is used to convert the internal representation of variables to the CSS representation.
+	 * For example, `var:preset|color|vivid-green-cyan` becomes `var(--wp--preset--color--vivid-green-cyan)`.
+	 *
+	 * @since 6.3.0
+	 * @param string $value The variable such as var:preset|color|vivid-green-cyan to convert.
+	 * @return string The converted variable.
+	 */
+	private static function convert_custom_properties( $value ) {
+		$prefix     = 'var:';
+		$prefix_len = strlen( $prefix );
+		$token_in   = '|';
+		$token_out  = '--';
+		if ( 0 === strpos( $value, $prefix ) ) {
+			$unwrapped_name = str_replace(
+				$token_in,
+				$token_out,
+				substr( $value, $prefix_len )
+			);
+			$value          = "var(--wp--$unwrapped_name)";
+		}
+
+		return $value;
+	}
+
+	/**
+	 * Given a tree, converts the internal representation of variables to the CSS representation.
+	 * It is recursive and modifies the input in-place.
+	 *
+	 * @since 6.3.0
+	 * @param array $tree   Input to process.
+	 * @return array The modified $tree.
+	 */
+	private static function resolve_custom_css_format( $tree ) {
+		$prefix = 'var:';
+
+		foreach ( $tree as $key => $data ) {
+			if ( is_string( $data ) && 0 === strpos( $data, $prefix ) ) {
+				$tree[ $key ] = self::convert_custom_properties( $data );
+			} elseif ( is_array( $data ) ) {
+				$tree[ $key ] = self::resolve_custom_css_format( $data );
+			}
+		}
+
+		return $tree;
+	}
+
 }
diff --git a/src/wp-includes/global-styles-and-settings.php b/src/wp-includes/global-styles-and-settings.php
index f5ea9ed179..4c016930b7 100644
--- a/src/wp-includes/global-styles-and-settings.php
+++ b/src/wp-includes/global-styles-and-settings.php
@@ -92,6 +92,8 @@ function wp_get_global_settings( $path = array(), $context = array() ) {
  * Gets the styles resulting of merging core, theme, and user data.
  *
  * @since 5.9.0
+ * @since 6.3.0 the internal format "var:preset|color|secondary" is always resolved
+ *              to the standard form "var(--wp--preset--font-size--small)".
  *
  * @param array $path    Path to the specific style to retrieve. Optional.
  *                       If empty, will return all styles.
@@ -115,7 +117,6 @@ function wp_get_global_styles( $path = array(), $context = array() ) {
 	if ( isset( $context['origin'] ) && 'base' === $context['origin'] ) {
 		$origin = 'theme';
 	}
-
 	$styles = WP_Theme_JSON_Resolver::get_merged_data( $origin )->get_raw_data()['styles'];
 
 	return _wp_array_get( $styles, $path, $styles );
diff --git a/tests/phpunit/tests/theme/wpThemeJson.php b/tests/phpunit/tests/theme/wpThemeJson.php
index 19212bc513..e43f99c969 100644
--- a/tests/phpunit/tests/theme/wpThemeJson.php
+++ b/tests/phpunit/tests/theme/wpThemeJson.php
@@ -1972,30 +1972,30 @@ class Tests_Theme_wpThemeJson extends WP_UnitTestCase {
 			'version' => WP_Theme_JSON::LATEST_SCHEMA,
 			'styles'  => array(
 				'color'    => array(
-					'text' => 'var:preset|color|dark-red',
+					'text' => 'var(--wp--preset--color--dark-red)',
 				),
 				'elements' => array(
 					'link' => array(
 						'color' => array(
-							'text'       => 'var:preset|color|dark-pink',
-							'background' => 'var:preset|color|dark-red',
+							'text'       => 'var(--wp--preset--color--dark-pink)',
+							'background' => 'var(--wp--preset--color--dark-red)',
 						),
 					),
 				),
 				'blocks'   => array(
 					'core/image' => array(
 						'filter' => array(
-							'duotone' => 'var:preset|duotone|blue-red',
+							'duotone' => 'var(--wp--preset--duotone--blue-red)',
 						),
 					),
 					'core/group' => array(
 						'color'    => array(
-							'text' => 'var:preset|color|dark-gray',
+							'text' => 'var(--wp--preset--color--dark-gray)',
 						),
 						'elements' => array(
 							'link' => array(
 								'color' => array(
-									'text' => 'var:preset|color|dark-pink',
+									'text' => 'var(--wp--preset--color--dark-pink)',
 								),
 							),
 						),
@@ -4706,4 +4706,69 @@ class Tests_Theme_wpThemeJson extends WP_UnitTestCase {
 			),
 		);
 	}
+
+	public function test_internal_syntax_is_converted_to_css_variables() {
+		$result = new WP_Theme_JSON(
+			array(
+				'version' => WP_Theme_JSON::LATEST_SCHEMA,
+				'styles'  => array(
+					'color'    => array(
+						'background' => 'var:preset|color|primary',
+						'text'       => 'var(--wp--preset--color--secondary)',
+					),
+					'elements' => array(
+						'link' => array(
+							'color' => array(
+								'background' => 'var:preset|color|pri',
+								'text'       => 'var(--wp--preset--color--sec)',
+							),
+						),
+					),
+					'blocks'   => array(
+						'core/post-terms' => array(
+							'typography' => array( 'fontSize' => 'var(--wp--preset--font-size--small)' ),
+							'color'      => array( 'background' => 'var:preset|color|secondary' ),
+						),
+						'core/navigation' => array(
+							'elements' => array(
+								'link' => array(
+									'color' => array(
+										'background' => 'var:preset|color|p',
+										'text'       => 'var(--wp--preset--color--s)',
+									),
+								),
+							),
+						),
+						'core/quote'      => array(
+							'typography' => array( 'fontSize' => 'var(--wp--preset--font-size--d)' ),
+							'color'      => array( 'background' => 'var:preset|color|d' ),
+							'variations' => array(
+								'plain' => array(
+									'typography' => array( 'fontSize' => 'var(--wp--preset--font-size--s)' ),
+									'color'      => array( 'background' => 'var:preset|color|s' ),
+								),
+							),
+						),
+					),
+				),
+			)
+		);
+		$styles = $result->get_raw_data()['styles'];
+
+		$this->assertEquals( 'var(--wp--preset--color--primary)', $styles['color']['background'], 'Top level: Assert the originally correct values are still correct.' );
+		$this->assertEquals( 'var(--wp--preset--color--secondary)', $styles['color']['text'], 'Top level: Assert the originally correct values are still correct.' );
+
+		$this->assertEquals( 'var(--wp--preset--color--pri)', $styles['elements']['link']['color']['background'], 'Element top level: Assert the originally correct values are still correct.' );
+		$this->assertEquals( 'var(--wp--preset--color--sec)', $styles['elements']['link']['color']['text'], 'Element top level: Assert the originally correct values are still correct.' );
+
+		$this->assertEquals( 'var(--wp--preset--font-size--small)', $styles['blocks']['core/post-terms']['typography']['fontSize'], 'Top block level: Assert the originally correct values are still correct.' );
+		$this->assertEquals( 'var(--wp--preset--color--secondary)', $styles['blocks']['core/post-terms']['color']['background'], 'Top block level: Assert the internal variables are convert to CSS custom variables.' );
+
+		$this->assertEquals( 'var(--wp--preset--color--p)', $styles['blocks']['core/navigation']['elements']['link']['color']['background'], 'Elements block level: Assert the originally correct values are still correct.' );
+		$this->assertEquals( 'var(--wp--preset--color--s)', $styles['blocks']['core/navigation']['elements']['link']['color']['text'], 'Elements block level: Assert the originally correct values are still correct.' );
+
+		$this->assertEquals( 'var(--wp--preset--font-size--s)', $styles['blocks']['core/quote']['variations']['plain']['typography']['fontSize'], 'Style variations: Assert the originally correct values are still correct.' );
+		$this->assertEquals( 'var(--wp--preset--color--s)', $styles['blocks']['core/quote']['variations']['plain']['color']['background'], 'Style variations: Assert the internal variables are convert to CSS custom variables.' );
+
+	}
 }