iOS 15 was recently announced with a bunch of new improvements and features that many users have been waiting for. One of these new features is the new, revamped Do Not Disturb section for iOS, now called Focus. Focus has different modes that allow you to customize and schedule your Do Not Disturb instances on your iOS device. This way, you can create a custom routine where you will only be notified about certain events and contacts that you want to get in touch with.
Using Focus on your iPhone | Apple Support
However, during any Focus mode, it can be annoying if you try to avoid a whitelisted contact or app from reaching you. You can fix this issue by using one of the solutions below.
The first thing you can do is simply remove the contact or app in question from your Focus Mode whitelist. This way, all subsequent messages and other notifications will be blocked by your Focus Mode that is currently enabled. You can use the guide below to easily remove a contact or app from your Focus Mode whitelist.
Open the Settings app and tap 'Focus'.