How to clear unread bullets after emails being read without need to restart the Mail app in iOS 14?

I have updated my iPad operating system from iOS 11.4 to iPadOS 14.3. In the new updated OS when I open the Mail app to see new received emails in my account inbox, blue bullets next to unread emails do not clear after emails being read. In order that such bullets clear immediately after reading unread emails, I have to hard-close the Mail app (kill the suspended Mail app in the background) and reopen the Mail app; in this case the problem is resolved.

I wonder whether there is a solution for such a bug so that I do not have to restart the Mail app each time.

PS: It is worth saying that I never faced such a bug in the older iOS version.