Hi Alex_stanciu21,
Thanks for contacting Apple Support Communities!
We understand that you're not seeing notifications for WhatsApp until you open the app, is that right?
Is this happening with any other apps? If not, you may consider checking your alert styles for WhatsApp to ensure they aren't scheduled to be delivered as a specific time or to be delivered in a group: Use notifications on your iPhone or iPad - Apple Support
"Change alert styles
- Go to Settings and tap Notifications.
- Select an app under Notification Style.
- Under Alerts, choose the alert style that you want. If you turn on Allow Notifications, choose when you want the notifications delivered—immediately or in the scheduled notification summary.
With iOS 15 and iPadOS 15 or later, you can turn on Critical Alerts for supported apps so notifications come through even if your iPhone is muted or you have a Focus set up."
If your settings are correct for your notifications, you may consider contacting WhatsApp support if this is the only app experiencing this behavior. There may be settings within the app itself that need to be adjusted and they'd be best suited to help. If you need help to locate their contact details, you can follow the steps outlined here to do so: How to contact an app developer - Apple Support
"Contact the developer of an iOS, iPadOS, or watchOS app
- Open the App Store on your iPhone or iPad.
- Search for the app, then tap it. If you can't find it, tap the account button or your photo at the top of the screen, tap Purchased, tap "Not on this [device]," then tap the app.
- The app's product page appears. Scroll to the Ratings & Reviews section, then tap App Support. If you don't see App Support, make sure that you're signed in with the correct Apple ID."
Take care!