diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php
index 574d0e9253..b5d38aae72 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php
@@ -232,6 +232,12 @@ class WP_REST_Attachments_Controller extends WP_REST_Posts_Controller {
 		 */
 		$prevent_unsupported_uploads = apply_filters( 'wp_prevent_unsupported_mime_type_uploads', true, $files['file']['type'] ?? null );
 
+		// When the client handles image processing (generate_sub_sizes is false),
+		// skip the server-side image editor support check.
+		if ( false === $request['generate_sub_sizes'] ) {
+			$prevent_unsupported_uploads = false;
+		}
+
 		// If the upload is an image, check if the server can handle the mime type.
 		if (
 			$prevent_unsupported_uploads &&
@@ -278,7 +284,7 @@ class WP_REST_Attachments_Controller extends WP_REST_Posts_Controller {
 		}
 
 		// Handle generate_sub_sizes parameter.
-		if ( isset( $request['generate_sub_sizes'] ) && ! $request['generate_sub_sizes'] ) {
+		if ( false === $request['generate_sub_sizes'] ) {
 			add_filter( 'intermediate_image_sizes_advanced', '__return_empty_array', 100 );
 			add_filter( 'fallback_intermediate_image_sizes', '__return_empty_array', 100 );
 			// Disable server-side EXIF rotation so the client can handle it.
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 9cd6887180..3b275b1e1d 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '7.0-beta4-61979';
+$wp_version = '7.0-beta4-61980';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.