Calendar App ios15

I'm on iOS 15.3 (iPhone11) My List View Icon is not there any more it looked like 3 lines with dots next to them and listed all my calendar entries for the month and now I have an icon like an oblong with 2 lines under it, all it does is show events for the day in the bottom half and days of the month in the top half. My Wife is also on iOS 15.3 (iPhone 7) and her phone still shows the list icon (3 lines with dots next to them). I don't like the split view and want the list view back - How can I get it back?