Given that a user's flagging performance is now evaluated based on flags handled recently, this feature, or something similar, is absolutely necessary.
If a user has enough flags declined in the last 7 days, they will begin to receive a warning message to review their recent flags before proceeding. This is designed to make the user check out their recent flags to see why they were declined, and think twice before continuing with the flag if they have a history of using flags improperly.
And if they continue to receive declined flags, they will be temporarily banned from flagging. When this happens, the users are again encouraged to review their recent flags to understand why they were banned.
This a huge problem when you can't find your recently handled flags. A user's flag history is listed chronologically based on when they flagged and not when the flag was handled, so it can be quite easy for the recently handled flags causing the ban to be buried in the history and intermingled with unhandled flags (which don't count towards the ban) and flags handled more than 7 days ago (and thus do not factor into the ban).
If we are going to encourage users to review their flagging performance to stave off a flag ban or learn from a ban, we need to provide a mechanism for them to be able to find the flags responsible for the ban, so a mechanism to filter your flags to find the recently handled flag is needed.