After updating iPhone to iOS 18 some of the apps are not sending notifications

Since downloading iOS 18 some of my apps are not sending notifications. I checked the apps I’m having issues with and the settings are correct for both the apps and in the notification settings. I’m thinking that it’s a bug in iOS that needs correcting or the app maker needs to rewrite some coding to support the new version of iOS. When will we see iOS 18.1 released?

[Re-Titled by Moderator]