Mail after iOS 15.1

Hello: After downloading iOS 15.1, I started to notice that some mail in All inboxes had another email on top—superimposed. It happens to all my email addresses. Not everyone email, maybe two out of 20. I have tried deleting ones I was able to decipher and knew they were not important but another one seems to take its place and slides down to the next email. There is one email in particular that continues to show up which makes me curious. I have tried to figure out a pattern but, honestly, it gets too confusing. I have tried a hard restart with no luck. Thanks for taking the time to read this and any suggestions will be appreciated.

Susan