We have a single 2016 Exchange 2016 CU19, on Win Server 2016 w/ Feb 2021 cumulative. I see "Security Update For Exchange Server 2016 CU19 (KB5000871)" as Successfully installed when I check Windows Update History. but yet, the Exchange zero-day report shows that I need to install KB5000871. Not sure why. that said, I love that you guys make these reports!