I noticed this also and called Apple support. Apparently, this is the new design. I think it makes the Calendar app both useless and irritating. I have complained to the support person and also submitted a complaint online. For example, my wife set up a calendar event for November 16th for herself with a two day alert. This morning I started receiving (since we share a calendar) calendar notice for this event. I can make it snooze for the standard 15 minutes, but of course it comes back, and back, and back. No way to tell it to wait until, say, 2 hours before the event. This is so irritating that I am gong to rollback to Catalina. I can't believe that someone did this. WHY?