diff --git a/plugins/woocommerce/changelog/remove-schema-from-additional-fields-filter b/plugins/woocommerce/changelog/remove-schema-from-additional-fields-filter
new file mode 100644
index 00000000000..a29db88b7c5
--- /dev/null
+++ b/plugins/woocommerce/changelog/remove-schema-from-additional-fields-filter
@@ -0,0 +1,5 @@
+Significance: patch
+Type: update
+Comment: This is behind a feature flag for now.
+
+
diff --git a/plugins/woocommerce/src/Blocks/Domain/Services/CheckoutFields.php b/plugins/woocommerce/src/Blocks/Domain/Services/CheckoutFields.php
index 3b9e92e4a16..0080be51288 100644
--- a/plugins/woocommerce/src/Blocks/Domain/Services/CheckoutFields.php
+++ b/plugins/woocommerce/src/Blocks/Domain/Services/CheckoutFields.php
@@ -538,12 +538,12 @@ class CheckoutFields {
 	 *
 	 * @param string           $key          The key of the field.
 	 * @param mixed            $field_value  The value of the field.
-	 * @param array            $field_schema The schema of the field.
 	 * @param \WP_REST_Request $request      The current API Request.
+	 * @param string|null      $address_type The type of address (billing, shipping, or null if the field is a contact/additional field).
 	 *
 	 * @since 8.6.0
 	 */
-	public function validate_field( $key, $field_value, $field_schema, $request ) {
+	public function validate_field( $key, $field_value, $request, $address_type = null ) {
 
 		$error = new \WP_Error();
 		try {
@@ -552,12 +552,12 @@ class CheckoutFields {
 			 *
 			 * @param \WP_Error        $error        A WP_Error that extensions may add errors to.
 			 * @param mixed            $field_value  The value of the field.
-			 * @param array            $field_schema The schema of the field.
 			 * @param \WP_REST_Request $request      The current API Request.
+			 * @param string|null      $address_type The type of address (billing, shipping, or null if the field is a contact/additional field).
 			 *
 			 * @since 8.6.0
 			 */
-			$filtered_result = apply_filters( 'woocommerce_blocks_validate_additional_field_' . $key, $error, $field_value, $field_schema, $request );
+			$filtered_result = apply_filters( 'woocommerce_blocks_validate_additional_field_' . $key, $error, $field_value, $request, $address_type );
 
 			if ( $error !== $filtered_result ) {
 
diff --git a/plugins/woocommerce/src/StoreApi/Schemas/V1/AbstractAddressSchema.php b/plugins/woocommerce/src/StoreApi/Schemas/V1/AbstractAddressSchema.php
index 3d38d4a1e09..3c541c1cebf 100644
--- a/plugins/woocommerce/src/StoreApi/Schemas/V1/AbstractAddressSchema.php
+++ b/plugins/woocommerce/src/StoreApi/Schemas/V1/AbstractAddressSchema.php
@@ -217,11 +217,12 @@ abstract class AbstractAddressSchema extends AbstractSchema {
 			// Check if a field is in the list of additional fields then validate the value against the custom validation rules defined for it.
 			// Skip additional validation if the schema validation failed.
 			if ( true === $result && in_array( $key, $additional_keys, true ) ) {
-				$result = $this->additional_fields_controller->validate_field( $key, $address[ $key ], $properties[ $key ], $request );
+				$address_type = 'shipping_address' === $this->title ? 'shipping' : 'billing';
+				$result       = $this->additional_fields_controller->validate_field( $key, $address[ $key ], $request, $address_type );
 			}
 
 			if ( is_wp_error( $result ) && $result->has_errors() ) {
-				$errors->add( $result->get_error_code(), $result->get_error_message() );
+				$errors->merge_from( $result );
 			}
 		}
 
diff --git a/plugins/woocommerce/src/StoreApi/Schemas/V1/CheckoutSchema.php b/plugins/woocommerce/src/StoreApi/Schemas/V1/CheckoutSchema.php
index 178e6b80321..41ea38bfcc6 100644
--- a/plugins/woocommerce/src/StoreApi/Schemas/V1/CheckoutSchema.php
+++ b/plugins/woocommerce/src/StoreApi/Schemas/V1/CheckoutSchema.php
@@ -373,7 +373,7 @@ class CheckoutSchema extends AbstractSchema {
 
 			// Only allow custom validation on fields that pass the schema validation.
 			if ( true === $result ) {
-				$result = $this->additional_fields_controller->validate_field( $key, $field_value, $properties[ $key ], $request );
+				$result = $this->additional_fields_controller->validate_field( $key, $field_value, $request );
 			}
 
 			if ( is_wp_error( $result ) && $result->has_errors() ) {