Thanks to my friend Max Sanna for the heads up on this one.
Indeed Max is right. The original end of mainstream support date for SfB Server 2019 was 2023, the normal 5 years of mainstream support (traditionally it was 5 years mainstream, 5 years extended). The intent was Office 2019 (client and server) would move to a 5 + 2 model
Now we are at a random ~5 years 3 months for mainstream support and ~1 year 9 months of extended support.
Exchange Server has also shifted to the same 2024 date for mainstream support
As has SharePoint server 2019, but its extended support is 2026. I’m not clear if SharePoint Server 2019 already had longer extended support of if this has shifted too. Why does SharePoint Server 2019 have a longer extended support date than Exchange and Skype for Business?
If anyone has any insights regarding the changes, please let me know. Either way, have another 3 months mainstream support on Microsoft.