Hi there, sbg1.
It appears that you're no longer receiving notifications from applications you use on your iPhone X, and we're glad to help with this.
Please test the issue after each step that you take:
Update your iPhone, iPad, or iPod touch - Apple Support -- Make sure that your iPhone X is up to date. The current iOS version is iOS 14.2. If your iPhone needs to be updated, please be sure to have a current backup: How to back up your iPhone, iPad, and iPod touch - Apple Support.
Download apps and games from the App Store - Apple Support -- Make sure that your applications are also up to date.
Use notifications on your iPhone, iPad, and iPod touch - Apple Support -- Check the notifications for each application that isn't providing notifications.
Use Do Not Disturb on your iPhone, iPad, and iPod touch - Apple Support -- Make sure that Do Not Disturb in turned on.
Set the date and time on iPhone - Apple Support -- Make sure that the date and time are correct and you're in the right time zone.
Learn the meaning of the iPhone status icons - Apple Support -- If you're using a VPN, disable it for a bit and see if you receive notifications.
If you're still not receiving notifications, please provide a sample of the applications you're not receiving notifications for, including any Apple apps.
Take care.