As of March 31, 2026, Microsoft removed outdated Windows 10 cumulative updates from MUC or other release channels. Windows 11 or Windows 8.1 are not affected by the decision.
The decision affects Windows 10 version 1507 to 22H2, and deleted CU will be marked as expired. Although preview updates and out-of-band updates are still available, I think MS will delete these updates sooner or later. Another problem is MS only marked outdated CU as expired for the version which has LTSB or LTSC edition, but MS also deleted outdated CU released for the version which has no LTSB or LTSC edition and official update history support page has no information.
Take version 1607 for example, KB5022838 which supports Home edition was removed, but MS kept KB5022289 because MS promised to help Atom Clover Trail users upgrade from 8.1 to 1607. MS also removed CU released for 1511, 1703, 1709, 1809, 2004, but it seems that 1803 is not affected.