diff --git a/packages/svelte/elements.d.ts b/packages/svelte/elements.d.ts
index e604505d96..b0c2fae2de 100644
--- a/packages/svelte/elements.d.ts
+++ b/packages/svelte/elements.d.ts
@@ -1268,7 +1268,7 @@ export interface HTMLMetaAttributes extends HTMLAttributes<HTMLMetaElement> {
 	charset?: string | undefined | null;
 	content?: string | undefined | null;
 	'http-equiv'?:
-	  | 'accept-ch'
+		| 'accept-ch'
 		| 'content-security-policy'
 		| 'content-type'
 		| 'default-style'
diff --git a/packages/svelte/src/internal/client/reactivity/batch.js b/packages/svelte/src/internal/client/reactivity/batch.js
index 2f05dca73b..82f1de67a9 100644
--- a/packages/svelte/src/internal/client/reactivity/batch.js
+++ b/packages/svelte/src/internal/client/reactivity/batch.js
@@ -187,8 +187,7 @@ export class Batch {
 		// if there are multiple batches, we are 'time travelling' —
 		// we need to undo the changes belonging to any batch
 		// other than the current one
-		// TODO this is wrong when flushSync is called while another batch is active, can be two when there's actually no time traveling
-		if (batches.size > 1) {
+		if (async_mode_flag && batches.size > 1) {
 			current_values = new Map();
 			batch_deriveds = new Map();
 
@@ -485,8 +484,8 @@ export class Batch {
  */
 export function flushSync(fn) {
 	if (async_mode_flag && active_effect !== null) {
-		// TODO why do we disallow this?
-		// e.flush_sync_in_effect();
+		// We disallow this because it creates super-hard to reason about stack trace and because it's generally a bad idea
+		e.flush_sync_in_effect();
 	}
 
 	var was_flushing_sync = is_flushing_sync;