vsterkin Thank you for reaching out for clarification. The entire lifecycle for LTSC 2021 is 5 years. Previously we marked LTSC as 5+5 (mainstream+extended) but in the LTSC world, there's no difference between mainstream and extended since LTSC does not receive new features - not even in the first 5 years. So we dropped the extended and changed LTSC from 2021 and forward to a full 5 year lifecycle. Any previous LTSB or LTSC version retains their existing 10 years lifecycle support, and IoT LTSC 2021 retinas its 10 years lifecycle support. But Windows 10 Enterprise LTSC 2021 is changed to 5 years.
You are correct that the /win10releaseinto page is wrong or misleading. IoT LTSC will be supported for 10 years, whilst LTSC Enterprise is 5 years, I will have that page clarified.
Thanks, and sorry for the confusion.