diff --git a/packages/backend/src/core/NoteCreateService.ts b/packages/backend/src/core/NoteCreateService.ts
index bd9d828357..31070e5f09 100644
--- a/packages/backend/src/core/NoteCreateService.ts
+++ b/packages/backend/src/core/NoteCreateService.ts
@@ -1050,12 +1050,13 @@ export class NoteCreateService implements OnApplicationShutdown {
 	}
 
 	@bindThis
-	public dispose(): void {
+	public async dispose(): Promise<void> {
 		this.#shutdownController.abort();
+		await this.updateNotesCountQueue.performAllNow();
 	}
 
 	@bindThis
-	public onApplicationShutdown(signal?: string | undefined): void {
-		this.dispose();
+	public async onApplicationShutdown(signal?: string | undefined): Promise<void> {
+		await this.dispose();
 	}
 }
diff --git a/packages/backend/src/misc/collapsed-queue.ts b/packages/backend/src/misc/collapsed-queue.ts
index 1d2750b19c..dee6df32bd 100644
--- a/packages/backend/src/misc/collapsed-queue.ts
+++ b/packages/backend/src/misc/collapsed-queue.ts
@@ -3,27 +3,41 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
+type Job<V> = {
+	value: V;
+	timer: NodeJS.Timeout;
+};
+
 export class CollapsedQueue<K, V> {
-	private jobs: Map<K, V> = new Map();
+	private jobs: Map<K, Job<V>> = new Map();
 
 	constructor(
 		private timeout: number,
 		private collapse: (oldValue: V, newValue: V) => V,
-		private doJob: (key: K, value: V) => void,
-	) { }
+		private perform: (key: K, value: V) => Promise<void>,
+	) {}
 
 	enqueue(key: K, value: V) {
 		if (this.jobs.has(key)) {
 			const old = this.jobs.get(key)!;
-			const merged = this.collapse(old, value);
-			this.jobs.set(key, merged);
+			const merged = this.collapse(old.value, value);
+			this.jobs.set(key, { ...old, value: merged });
 		} else {
-			this.jobs.set(key, value);
-			setTimeout(() => {
-				const value = this.jobs.get(key)!;
+			const timer = setTimeout(() => {
+				const job = this.jobs.get(key)!;
 				this.jobs.delete(key);
-				this.doJob(key, value);
+				this.perform(key, job.value);
 			}, this.timeout);
+			this.jobs.set(key, { value, timer });
 		}
 	}
+
+	async performAllNow() {
+		const entries = [...this.jobs.entries()];
+		this.jobs.clear();
+		for (const [_key, job] of entries) {
+			clearTimeout(job.timer);
+		}
+		await Promise.allSettled(entries.map(([key, job]) => this.perform(key, job.value)));
+	}
 }
diff --git a/packages/backend/src/queue/processors/InboxProcessorService.ts b/packages/backend/src/queue/processors/InboxProcessorService.ts
index 69f868fcc8..fa929a4d77 100644
--- a/packages/backend/src/queue/processors/InboxProcessorService.ts
+++ b/packages/backend/src/queue/processors/InboxProcessorService.ts
@@ -4,7 +4,7 @@
  */
 
 import { URL } from 'node:url';
-import { Injectable } from '@nestjs/common';
+import { Injectable, OnApplicationShutdown } from '@nestjs/common';
 import httpSignature from '@peertube/http-signature';
 import * as Bull from 'bullmq';
 import type Logger from '@/logger.js';
@@ -26,10 +26,10 @@ import { JsonLdService } from '@/core/activitypub/JsonLdService.js';
 import { ApInboxService } from '@/core/activitypub/ApInboxService.js';
 import { bindThis } from '@/decorators.js';
 import { IdentifiableError } from '@/misc/identifiable-error.js';
-import { QueueLoggerService } from '../QueueLoggerService.js';
-import type { InboxJobData } from '../types.js';
 import { CollapsedQueue } from '@/misc/collapsed-queue.js';
 import { MiNote } from '@/models/Note.js';
+import { QueueLoggerService } from '../QueueLoggerService.js';
+import type { InboxJobData } from '../types.js';
 
 type UpdateInstanceJob = {
 	latestRequestReceivedAt: Date,
@@ -37,7 +37,7 @@ type UpdateInstanceJob = {
 };
 
 @Injectable()
-export class InboxProcessorService {
+export class InboxProcessorService implements OnApplicationShutdown {
 	private logger: Logger;
 	private updateInstanceQueue: CollapsedQueue<MiNote['id'], UpdateInstanceJob>;
 
@@ -254,4 +254,14 @@ export class InboxProcessorService {
 			suspensionState: job.shouldUnsuspend ? 'none' : undefined,
 		});
 	}
+
+	@bindThis
+	public async dispose(): Promise<void> {
+		await this.updateInstanceQueue.performAllNow();
+	}
+
+	@bindThis
+	async onApplicationShutdown(signal?: string) {
+		await this.dispose();
+	}
 }