Just as my previous post said, install the latest SSU KB4566425.
Then, install KB500087 from here:
Description of the security update for Microsoft Exchange Server 2019, 2016, and 2013: March 2, 2021 (KB5000871)
https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-microsoft-exchange-server-2019-2016-and-2013-march-2-2021-kb5000871-9800a6bb-0a21-4ee7-b9da-fa85b3e1d23b
-------------------------------------------------------------------------------------
If the Answer is helpful, please click "Accept Answer" and upvote it.
Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.