I'm on iOS 26.2 and I have this issue with delayed notifications (after 20 minutes of inactivity of iPhone). Will this be fixed? It's basic functionality and it doesn't work as it should.

Same here on iOS 18.7.3 and iOS 26.3 Beta 2.

Have you found a fix for this bug? I think that it's because iPhone go to deep sleep after some time when screen is locked and device is inactive. This bug happens on both iOS 18.7 and iOS 26.