Download the Media Creation Tool (not the Update Assistant).

Visit the official Microsoft Software Download page (formerly Media Creation Tool).

Go to Microsoft’s Windows 10 Update Assistant page (search "Download Windows 10" – the official Microsoft link).

Select "Create installation media (USB flash drive, DVD, or ISO file) for another PC."

Search for "2022-xx Cumulative Update for Windows 10 Version 21H2" (choose the latest month before support ended).