fix

packages/svelte/src/compiler/phases/3-transform/client/visitors/Attachment.js

@@ -9,26 +9,18 @@ import * as b from '../../../../utils/builders.js';
  */
 export function Attachment(node, context) {
 	for (const attachment of node.attachments) {
-		if (attachment.type === 'SpreadElement') {
 		context.state.init.push(
 			b.stmt(
 				b.call(
-						'$.attach_all',
+					'$.attach',
 					context.state.node,
-						b.thunk(/** @type {Expression} */ (context.visit(attachment.argument)))
+					b.thunk(
+						/** @type {Expression} */ (
+							context.visit(attachment.type === 'SpreadElement' ? attachment.argument : attachment)
 						)
 					)
-			);
-		} else {
-			context.state.init.push(
-				b.stmt(
-					b.call(
-						'$.attach',
-						context.state.node,
-						b.thunk(/** @type {Expression} */ (context.visit(attachment)))
 				)
 			)
 		);
 	}
-	}
 }

packages/svelte/src/internal/client/dom/elements/attachments.js

@@ -11,7 +11,7 @@ export function attach(node, get_fn) {
 		if (Array.isArray(attachment)) {
 			for (const fn of attachment) {
 				if (fn) {
-					$effect(() => fn(node));
+					effect(() => fn(node));
 				}
 			}
 		} else if (attachment) {